Version 1.2.1 imported1.2.1

git-archimport-id: mdk@sv.gnu.org/mdk--devel--1--patch-1

29 files changed, 6292 insertions, 0 deletions

diff --git a/doc/Makefile.am b/doc/Makefile.am
new file mode 100644
index 0000000..b2b73f0
--- /dev/null
+++ b/doc/Makefile.am
@@ -0,0 +1,23 @@
+## Process this file with automake to produce Makefile.in
+
+# Copyright (C) 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
+#
+# This file is free software; as a special exception the author gives
+# unlimited permission to copy and/or distribute it, with or without
+# modifications, as long as this notice is preserved.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+# $Id: Makefile.am,v 1.11 2004/08/06 12:14:07 jao Exp $
+
+SUBDIRS = img
+SUFFIXES = .html
+
+info_TEXINFOS = mdk.texi
+mdk_TEXINFOS = mdk_intro.texi mdk_ack.texi mdk_tut.texi mdk_gstart.texi \
+               mdk_mixvm.texi mdk_emacs.texi mdk_mixasm.texi mdk_bugs.texi \
+               mdk_index.texi mdk_gmixvm.texi mdk_install.texi \
+               mdk_mixguile.texi mdk_copying.texi mdk_findex.texi
+
diff --git a/doc/gendocs.sh b/doc/gendocs.sh
new file mode 100755
index 0000000..7b8a3ca
--- /dev/null
+++ b/doc/gendocs.sh
@@ -0,0 +1,285 @@
+#!/bin/sh
+# gendocs.sh -- generate a GNU manual in many formats.  This script is
+#   mentioned in maintain.texi.  See the help message below for usage details.
+# $Id: gendocs.sh,v 1.4 2005/09/20 20:18:58 jao Exp $
+# 
+# Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, you can either send email to this
+# program's maintainer or write to: The Free Software Foundation,
+# Inc.; 51 Franklin Street, Fifth Floor; Boston, MA 02110-1301, USA.
+#
+# Original author: Mohit Agarwal.
+# Send bug reports and any other correspondence to bug-texinfo@gnu.org.
+
+prog="`basename \"$0\"`"
+srcdir=`pwd`
+
+scripturl="http://savannah.gnu.org/cgi-bin/viewcvs/texinfo/texinfo/util/gendocs.sh"
+templateurl="http://savannah.gnu.org/cgi-bin/viewcvs/texinfo/texinfo/util/gendocs_template"
+
+: ${MAKEINFO="makeinfo"}
+: ${TEXI2DVI="texi2dvi -t @finalout"}
+: ${DVIPS="dvips"}
+: ${DOCBOOK2TXT="docbook2txt"}
+: ${DOCBOOK2HTML="docbook2html"}
+: ${DOCBOOK2PDF="docbook2pdf"}
+: ${DOCBOOK2PS="docbook2ps"}
+: ${GENDOCS_TEMPLATE_DIR="."}
+unset CDPATH
+
+rcs_revision='$Revision: 1.4 $'
+rcs_version=`set - $rcs_revision; echo $2`
+program=`echo $0 | sed -e 's!.*/!!'`
+version="gendocs.sh $rcs_version
+
+Copyright (C) 2005 Free Software Foundation, Inc.
+There is NO warranty.  You may redistribute this software
+under the terms of the GNU General Public License.
+For more information about these matters, see the files named COPYING."
+
+usage="Usage: $prog [OPTION]... PACKAGE MANUAL-TITLE
+
+Generate various output formats from PACKAGE.texinfo (or .texi or .txi) source.
+See the GNU Maintainers document for a more extensive discussion:
+  http://www.gnu.org/prep/maintain_toc.html
+
+Options:
+  -o OUTDIR   write files into OUTDIR, instead of manual/.
+  --docbook   convert to DocBook too (xml, txt, html, pdf and ps).
+  --html ARG  pass indicated ARG to makeinfo for HTML targets.
+  --help      display this help and exit successfully.
+  --version   display version information and exit successfully.
+
+Simple example: $prog emacs \"GNU Emacs Manual\"
+
+Typical sequence:
+  cd YOURPACKAGESOURCE/doc
+  wget \"$scripturl\"
+  wget \"$templateurl\"
+  $prog YOURMANUAL \"GNU YOURMANUAL - One-line description\"
+
+Output will be in a new subdirectory \"manual\" (by default, use -o OUTDIR
+to override).  Move all the new files into your web CVS tree, as
+explained in the Web Pages node of maintain.texi.
+
+MANUAL-TITLE is included as part of the HTML <title> of the overall
+manual/index.html file.  It should include the name of the package being
+documented.  manual/index.html is created by substitution from the file
+$GENDOCS_TEMPLATE_DIR/gendocs_template.  (Feel free to modify the
+generic template for your own purposes.)
+
+If you have several manuals, you'll need to run this script several
+times with different YOURMANUAL values, specifying a different output
+directory with -o each time.  Then write (by hand) an overall index.html
+with links to them all.
+
+You can set the environment variables MAKEINFO, TEXI2DVI, and DVIPS to
+control the programs that get executed, and GENDOCS_TEMPLATE_DIR to
+control where the gendocs_template file is looked for.
+
+Email bug reports or enhancement requests to bug-texinfo@gnu.org.
+"
+
+calcsize()
+{
+  size="`ls -ksl $1 | awk '{print $1}'`"
+  echo $size
+}
+
+outdir=manual
+html=
+PACKAGE=
+MANUAL_TITLE=
+
+while test $# -gt 0; do
+  case $1 in
+    --help) echo "$usage"; exit 0;;
+    --version) echo "$version"; exit 0;;
+    -o) shift; outdir=$1;;
+    --docbook) docbook=yes;;
+    --html) shift; html=$1;;
+    -*)
+      echo "$0: Unknown or ambiguous option \`$1'." >&2
+      echo "$0: Try \`--help' for more information." >&2
+      exit 1;;
+    *)
+      if test -z "$PACKAGE"; then
+        PACKAGE=$1
+      elif test -z "$MANUAL_TITLE"; then
+        MANUAL_TITLE=$1
+      else
+        echo "$0: extra non-option argument \`$1'." >&2
+        exit 1
+      fi;;
+  esac
+  shift
+done
+
+if test -s $srcdir/$PACKAGE.texinfo; then
+  srcfile=$srcdir/$PACKAGE.texinfo
+elif test -s $srcdir/$PACKAGE.texi; then
+  srcfile=$srcdir/$PACKAGE.texi
+elif test -s $srcdir/$PACKAGE.txi; then
+  srcfile=$srcdir/$PACKAGE.txi
+else
+  echo "$0: cannot find .texinfo or .texi or .txi for $PACKAGE in $srcdir." >&2
+  exit 1
+fi
+
+if test ! -r $GENDOCS_TEMPLATE_DIR/gendocs_template; then
+  echo "$0: cannot read $GENDOCS_TEMPLATE_DIR/gendocs_template." >&2
+  echo "$0: it is available from $templateurl." >&2
+  exit 1
+fi
+
+echo Generating output formats for $srcfile
+
+cmd="${MAKEINFO} -o $PACKAGE.info $srcfile"
+echo "Generating info files... ($cmd)"
+eval $cmd
+mkdir -p $outdir/
+tar czf $outdir/$PACKAGE.info.tar.gz $PACKAGE.info*
+info_tgz_size="`calcsize $outdir/$PACKAGE.info.tar.gz`"
+# do not mv the info files, there's no point in having them available
+# separately on the web.
+
+cmd="${TEXI2DVI} $srcfile"
+echo "Generating dvi ... ($cmd)"
+eval $cmd
+
+# now, before we compress dvi:
+echo Generating postscript...
+${DVIPS} $PACKAGE -o
+gzip -f -9 $PACKAGE.ps
+ps_gz_size="`calcsize $PACKAGE.ps.gz`"
+mv $PACKAGE.ps.gz $outdir/
+
+# compress/finish dvi:
+gzip -f -9 $PACKAGE.dvi
+dvi_gz_size="`calcsize $PACKAGE.dvi.gz`"
+mv $PACKAGE.dvi.gz $outdir/
+
+cmd="${TEXI2DVI} --pdf $srcfile"
+echo "Generating pdf ... ($cmd)"
+eval $cmd
+pdf_size="`calcsize $PACKAGE.pdf`"
+mv $PACKAGE.pdf $outdir/
+
+cmd="${MAKEINFO} -o $PACKAGE.txt --no-split --no-headers $srcfile"
+echo "Generating ASCII... ($cmd)"
+eval $cmd
+ascii_size="`calcsize $PACKAGE.txt`"
+gzip -f -9 -c $PACKAGE.txt >$outdir/$PACKAGE.txt.gz
+ascii_gz_size="`calcsize $outdir/$PACKAGE.txt.gz`"
+mv $PACKAGE.txt $outdir/
+
+cmd="${MAKEINFO} --no-split --html -o $PACKAGE.html $html $srcfile"
+echo "Generating monolithic html... ($cmd)"
+rm -rf $PACKAGE.html  # in case a directory is left over
+eval $cmd
+html_mono_size="`calcsize $PACKAGE.html`"
+gzip -f -9 -c $PACKAGE.html >$outdir/$PACKAGE.html.gz
+html_mono_gz_size="`calcsize $outdir/$PACKAGE.html.gz`"
+mv $PACKAGE.html $outdir/
+
+cmd="${MAKEINFO} --html -o $PACKAGE.html $html $srcfile"
+echo "Generating html by node... ($cmd)"
+eval $cmd
+split_html_dir=$PACKAGE.html
+(
+  cd ${split_html_dir} || exit 1
+  tar -czf ../$outdir/${PACKAGE}.html_node.tar.gz -- *.html
+)
+html_node_tgz_size="`calcsize $outdir/${PACKAGE}.html_node.tar.gz`"
+rm -f $outdir/html_node/*.html
+mkdir -p $outdir/html_node/
+mv ${split_html_dir}/*.html $outdir/html_node/
+rmdir ${split_html_dir}
+
+echo Making .tar.gz for sources...
+srcfiles=`ls *.texinfo *.texi *.txi *.eps 2>/dev/null`
+tar cvzfh $outdir/$PACKAGE.texi.tar.gz $srcfiles
+texi_tgz_size="`calcsize $outdir/$PACKAGE.texi.tar.gz`"
+
+if test -n "$docbook"; then
+  cmd="${MAKEINFO} -o - --docbook $srcfile > ${srcdir}/$PACKAGE-db.xml"
+  echo "Generating docbook XML... $(cmd)"
+  eval $cmd
+  docbook_xml_size="`calcsize $PACKAGE-db.xml`"
+  gzip -f -9 -c $PACKAGE-db.xml >$outdir/$PACKAGE-db.xml.gz
+  docbook_xml_gz_size="`calcsize $outdir/$PACKAGE-db.xml.gz`"
+  mv $PACKAGE-db.xml $outdir/
+
+  cmd="${DOCBOOK2HTML} -o $split_html_db_dir ${outdir}/$PACKAGE-db.xml"
+  echo "Generating docbook HTML... ($cmd)"
+  eval $cmd
+  split_html_db_dir=html_node_db
+  (
+    cd ${split_html_db_dir} || exit 1
+    tar -czf ../$outdir/${PACKAGE}.html_node_db.tar.gz -- *.html
+  )
+  html_node_db_tgz_size="`calcsize $outdir/${PACKAGE}.html_node_db.tar.gz`"
+  rm -f $outdir/html_node_db/*.html
+  mkdir -p $outdir/html_node_db
+  mv ${split_html_db_dir}/*.html $outdir/html_node_db/
+  rmdir ${split_html_db_dir}
+
+  cmd="${DOCBOOK2TXT} ${outdir}/$PACKAGE-db.xml"
+  echo "Generating docbook ASCII... ($cmd)"
+  eval $cmd
+  docbook_ascii_size="`calcsize $PACKAGE-db.txt`"
+  mv $PACKAGE-db.txt $outdir/
+
+  cmd="${DOCBOOK2PS} ${outdir}/$PACKAGE-db.xml"
+  echo "Generating docbook PS... $(cmd)"
+  eval $cmd
+  gzip -f -9 -c $PACKAGE-db.ps >$outdir/$PACKAGE-db.ps.gz
+  docbook_ps_gz_size="`calcsize $outdir/$PACKAGE-db.ps.gz`"
+  mv $PACKAGE-db.ps $outdir/
+
+  cmd="${DOCBOOK2PDF} ${outdir}/$PACKAGE-db.xml"
+  echo "Generating docbook PDF... ($cmd)"
+  eval $cmd
+  docbook_pdf_size="`calcsize $PACKAGE-db.pdf`"
+  mv $PACKAGE-db.pdf $outdir/
+fi
+
+echo Writing index file...
+curdate="`date '+%B %d, %Y'`"
+sed \
+   -e "s!%%TITLE%%!$MANUAL_TITLE!g" \
+   -e "s!%%DATE%%!$curdate!g" \
+   -e "s!%%PACKAGE%%!$PACKAGE!g" \
+   -e "s!%%HTML_MONO_SIZE%%!$html_mono_size!g" \
+   -e "s!%%HTML_MONO_GZ_SIZE%%!$html_mono_gz_size!g" \
+   -e "s!%%HTML_NODE_TGZ_SIZE%%!$html_node_tgz_size!g" \
+   -e "s!%%INFO_TGZ_SIZE%%!$info_tgz_size!g" \
+   -e "s!%%DVI_GZ_SIZE%%!$dvi_gz_size!g" \
+   -e "s!%%PDF_SIZE%%!$pdf_size!g" \
+   -e "s!%%PS_GZ_SIZE%%!$ps_gz_size!g" \
+   -e "s!%%ASCII_SIZE%%!$ascii_size!g" \
+   -e "s!%%ASCII_GZ_SIZE%%!$ascii_gz_size!g" \
+   -e "s!%%TEXI_TGZ_SIZE%%!$texi_tgz_size!g" \
+   -e "s!%%DOCBOOK_HTML_NODE_TGZ_SIZE%%!$html_node_db_tgz_size!g" \
+   -e "s!%%DOCBOOK_ASCII_SIZE%%!$docbook_ascii_size!g" \
+   -e "s!%%DOCBOOK_PS_GZ_SIZE%%!$docbook_ps_gz_size!g" \
+   -e "s!%%DOCBOOK_PDF_SIZE%%!$docbook_pdf_size!g" \
+   -e "s!%%DOCBOOK_XML_SIZE%%!$docbook_xml_size!g" \
+   -e "s!%%DOCBOOK_XML_GZ_SIZE%%!$docbook_xml_gz_size!g" \
+   -e "s,%%SCRIPTURL%%,$scripturl,g" \
+   -e "s!%%SCRIPTNAME%%!$prog!g" \
+$GENDOCS_TEMPLATE_DIR/gendocs_template >$outdir/index.html
+
+echo "Done!  See $outdir/ subdirectory for new files."
diff --git a/doc/gendocs_template b/doc/gendocs_template
new file mode 100644
index 0000000..3fd6fd2
--- /dev/null
+++ b/doc/gendocs_template
@@ -0,0 +1,100 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<!-- $Id: gendocs_template,v 1.4 2005/09/20 20:18:58 jao Exp $ -->
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
+
+<head>
+<title>%%TITLE%% - GNU Project - Free Software Foundation (FSF)</title>
+<meta http-equiv="content-type" content='text/html; charset=utf-8' />
+<link rel="stylesheet" type="text/css" href="/gnu.css" />
+<link rev="made" href="webmasters@gnu.org" />
+</head>
+
+<!-- This document is in XML, and xhtml 1.0 -->
+<!-- Please make sure to properly nest your tags -->
+<!-- and ensure that your final document validates -->
+<!-- consistent with W3C xhtml 1.0 and CSS standards -->
+<!-- See validator.w3.org -->
+
+<body>
+
+<h3>%%TITLE%%</h3>
+
+<address>Free Software Foundation</address>
+<address>last updated %%DATE%%</address>
+<p>
+<a href="/graphics/gnu-head.jpg">
+	<img src="/graphics/gnu-head-sm.jpg"
+	alt=" [image of the head of a GNU] "
+	width="129" height="122" />
+</a>
+<a href="/philosophy/gif.html">(no gifs due to patent problems)</a>
+</p>
+<hr />
+
+<p>This manual (%%PACKAGE%%) is available in the following formats:</p>
+
+<ul>
+  <li><a href="%%PACKAGE%%.html">HTML
+      (%%HTML_MONO_SIZE%%K characters)</a> - entirely on one web page.</li>
+  <li><a href="html_node/index.html">HTML</a> - with one web page per
+      node.</li>
+  <li><a href="%%PACKAGE%%.html.gz">HTML compressed
+      (%%HTML_MONO_GZ_SIZE%%K gzipped characters)</a> - entirely on
+      one web page.</li>
+  <li><a href="%%PACKAGE%%.html_node.tar.gz">HTML compressed
+      (%%HTML_NODE_TGZ_SIZE%%K gzipped tar file)</a> -
+      with one web page per node.</li>
+  <li><a href="%%PACKAGE%%.info.tar.gz">Info document
+      (%%INFO_TGZ_SIZE%%K characters gzipped tar file)</a>.</li>
+  <li><a href="%%PACKAGE%%.txt">ASCII text
+      (%%ASCII_SIZE%%K characters)</a>.</li>
+  <li><a href="%%PACKAGE%%.txt.gz">ASCII text compressed
+      (%%ASCII_GZ_SIZE%%K gzipped characters)</a>.</li>
+  <li><a href="%%PACKAGE%%.dvi.gz">TeX dvi file
+      (%%DVI_GZ_SIZE%%K characters gzipped)</a>.</li>
+  <li><a href="%%PACKAGE%%.ps.gz">PostScript file
+      (%%PS_GZ_SIZE%%K characters gzipped)</a>.</li>
+  <li><a href="%%PACKAGE%%.pdf">PDF file
+      (%%PDF_SIZE%%K characters)</a>.</li>
+  <li><a href="%%PACKAGE%%.texi.tar.gz">Texinfo source
+      (%%TEXI_TGZ_SIZE%%K characters gzipped tar file)</a></li>
+</ul>
+
+<p>(This page generated by the <a href="%%SCRIPTURL%%">%%SCRIPTNAME%%
+script</a>.)</p>
+
+<div class="copyright">
+<p>
+Return to the <a href="/home.html">GNU Project home page</a>.
+</p>
+
+<p>
+Please send FSF &amp; GNU inquiries to
+<a href="mailto:gnu@gnu.org"><em>gnu@gnu.org</em></a>.
+There are also <a href="/home.html#ContactInfo">other ways to contact</a>
+the FSF.
+<br />
+Please send broken links and other corrections (or suggestions) to
+<a href="mailto:webmasters@gnu.org"><em>webmasters@gnu.org</em></a>.
+</p>
+
+<p>
+Copyright (C) 2004 Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02111, USA
+<br />
+Verbatim copying and distribution of this entire article is
+permitted in any medium, provided this notice is preserved.
+</p>
+
+<p>
+Updated:
+<!-- timestamp start -->
+$Date: 2005/09/20 20:18:58 $ $Author: jao $
+<!-- timestamp end -->
+</p>
+</div>
+
+</body>
+</html>
diff --git a/doc/img/Makefile.am b/doc/img/Makefile.am
new file mode 100644
index 0000000..f59647e
--- /dev/null
+++ b/doc/img/Makefile.am
@@ -0,0 +1,16 @@
+## Process this file with automake to produce Makefile.in
+
+# Copyright (C) 2001, 2004 Free Software Foundation, Inc.
+#
+# This file is free software; as a special exception the author gives
+# unlimited permission to copy and/or distribute it, with or without
+# modifications, as long as this notice is preserved.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+EXTRA_DIST = ss_mix.jpg ss_mixal.jpg ss_devices.jpg ss_worddlg.jpg \
+             ss_mix.txt ss_devform.jpg ss_extprog.jpg ss_symbols.jpg \
+             ss_devdir.jpg ss_split.jpg
+
diff --git a/doc/img/ss_devdir.jpg b/doc/img/ss_devdir.jpg
new file mode 100644
index 0000000..009fa43
--- /dev/null
+++ b/doc/img/ss_devdir.jpg
diff --git a/doc/img/ss_devform.jpg b/doc/img/ss_devform.jpg
new file mode 100644
index 0000000..a93e5a0
--- /dev/null
+++ b/doc/img/ss_devform.jpg
diff --git a/doc/img/ss_devices.jpg b/doc/img/ss_devices.jpg
new file mode 100644
index 0000000..ecb3679
--- /dev/null
+++ b/doc/img/ss_devices.jpg
diff --git a/doc/img/ss_extprog.jpg b/doc/img/ss_extprog.jpg
new file mode 100644
index 0000000..f5607de
--- /dev/null
+++ b/doc/img/ss_extprog.jpg
diff --git a/doc/img/ss_mix.jpg b/doc/img/ss_mix.jpg
new file mode 100644
index 0000000..8b4080f
--- /dev/null
+++ b/doc/img/ss_mix.jpg
diff --git a/doc/img/ss_mix.txt b/doc/img/ss_mix.txt
new file mode 100644
index 0000000..757026e
--- /dev/null
+++ b/doc/img/ss_mix.txt
@@ -0,0 +1,31 @@
+|-----------------------------------------------------------|
+|   Menu       	       	  	         	            |
+|-----------------------------------------------------------|
+|            	      	       	         	            |
+|            	      	       	         	            |
+|            	      	       	         	            |
+|      	   	      	       	         	            |
+|               MIXVM / MIXAL / Devices  	            |
+|                     	       	         	            |
+|          	   	       	         	            |
+|                              	         	            |
+|      			       	         	            |
+|      			       	         	            |
+|                              	         	            |
+|-----------------------------------------------------------|
+|      				         	            |
+|                     Command output     	            |
+|      				    		            |
+|      				    		            |
+|                                                           |
+|-----------------------------------------------------------|
+|                     Command prompt               	    |
+|-----------------------------------------------------------|
+|  Status bar						    |
+|-----------------------------------------------------------|
+       							    
+       							    
+       							    
+
+
+
diff --git a/doc/img/ss_mixal.jpg b/doc/img/ss_mixal.jpg
new file mode 100644
index 0000000..5227b5a
--- /dev/null
+++ b/doc/img/ss_mixal.jpg
diff --git a/doc/img/ss_split.jpg b/doc/img/ss_split.jpg
new file mode 100644
index 0000000..66fd4a7
--- /dev/null
+++ b/doc/img/ss_split.jpg
diff --git a/doc/img/ss_symbols.jpg b/doc/img/ss_symbols.jpg
new file mode 100644
index 0000000..6a0e827
--- /dev/null
+++ b/doc/img/ss_symbols.jpg
diff --git a/doc/img/ss_worddlg.jpg b/doc/img/ss_worddlg.jpg
new file mode 100644
index 0000000..fc19000
--- /dev/null
+++ b/doc/img/ss_worddlg.jpg
diff --git a/doc/mdk.texi b/doc/mdk.texi
new file mode 100644
index 0000000..ce86b37
--- /dev/null
+++ b/doc/mdk.texi
@@ -0,0 +1,248 @@
+\input texinfo  @c -*-texinfo-*-
+@c %**start of header
+@setfilename mdk.info
+@settitle GNU MIX Development Kit (mdk)
+@syncodeindex pg cp
+@finalout
+@setchapternewpage odd
+@c $Id: mdk.texi,v 1.28 2005/09/20 21:00:22 jao Exp $
+@c %**end of header
+
+@set UPDATED September, 2005
+@set EDITION 1.2.1
+@set VERSION 1.2.1
+@set JAO Jose Antonio Ortega Ruiz
+@set PHILIP Philip E. King
+@set PIETER Pieter E. J. Pareit
+@set MIKE Michael Scholz
+
+@copying
+This manual is for GNU MDK (version @value{VERSION}, @value{UPDATED}),
+a set of utilities for developing programs using Donald Knuth's MIX
+mythical computer and MIXAL, its assembly language.
+
+Copyright @copyright{} 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+
+@quotation
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with the Front-Cover Texts being ``A GNU Manual,''
+and with the Back-Cover Texts as in (a) below.  A copy of the
+license is included in the section entitled ``GNU Free Documentation
+License.''
+
+(a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
+this GNU Manual, like GNU software.  Copies published by the Free
+Software Foundation raise funds for GNU development.''
+@end quotation
+@end copying
+
+@dircategory GNU programming tools
+@direntry
+* MDK: (mdk).           The GNU MIX Development Kit.
+@end direntry
+
+
+@footnotestyle separate
+
+@titlepage
+@title GNU MDK
+@subtitle GNU MIX Development Kit
+@subtitle Edition @value{EDITION}, for GNU @sc{mdk} Version @value{VERSION}
+@subtitle @value{UPDATED}
+@author by @value{JAO} (@email{jao@@gnu.org})
+@page
+@vskip 0pt plus 1filll
+@insertcopying
+@end titlepage
+
+@shortcontents
+@contents
+
+@ifnottex
+@node Top, Introduction, (dir), (dir)
+
+@insertcopying
+
+GNU MDK was written and designed by @value{JAO}.
+
+@value{PIETER} is the author of the Emacs @code{MIXAL} mode
+(@pxref{MIXAL mode}), and has also contributed many bug fixes.
+
+@value{PHILIP} has contributed to this package development with many
+helpful discussions, as well as actual code (@pxref{GUD integration}).
+
+@value{MIKE} is the author of the German translation of @sc{mdk}'s
+user interface.
+
+@end ifnottex
+
+@menu
+* Introduction::
+* Acknowledgments::
+* Installing MDK::              Installing GNU MDK from the source tarball.
+* MIX and MIXAL tutorial::      Learn the innards of MIX and MIXAL.
+* Getting started::             Basic usage of the @sc{mdk} tools.
+* Emacs tools::                 Programming the MIX using Emacs.
+* mixasm::                      Invoking the MIXAL assembler.
+* mixvm::                       Invoking and using the MIX virtual machine.
+* gmixvm::                      Invoking and using the GTK+ virtual machine.
+* mixguile::                    Invoking and using the Scheme virtual machine.
+* Problems::                    Reporting bugs.
+* Copying::                     @sc{mdk} licensing terms.
+* Concept Index::               Index of concepts.
+* Instructions and commands::   Index of MIXAL instructions and MIXVM commands.
+
+
+
+@detailmenu
+ --- The Detailed Node Listing ---
+
+Installing @sc{mdk}
+
+* Download::
+* Requirements::
+* Basic installation::
+* Emacs support::
+* Special configure flags::
+* Supported platforms::
+
+MIX and MIXAL tutorial
+
+* The MIX computer::            Architecture and instruction set
+                                of the MIX computer.
+* MIXAL::                       The MIX assembly language.
+
+The MIX computer
+
+* MIX architecture::
+* MIX instruction set::
+
+MIX instruction set
+
+* Instruction structure::
+* Loading operators::
+* Storing operators::
+* Arithmetic operators::
+* Address transfer operators::
+* Comparison operators::
+* Jump operators::
+* Input-output operators::
+* Conversion operators::
+* Shift operators::
+* Miscellaneous operators::
+* Execution times::
+
+MIXAL
+
+* Basic structure::             Writing basic MIXAL programs.
+* MIXAL directives::            Assembler directives.
+* Expressions::                 Evaluation of expressions.
+* W-expressions::               Evaluation of w-expressions.
+* Local symbols::               Special symbol table entries.
+* Literal constants::           Specifying an immediate operand.
+
+Getting started
+
+* Writing a source file::       A sample MIXAL source file.
+* Compiling::                   Using @code{mixasm} to compile source
+                                files into binary format.
+* Running the program::         Running and debugging your programs.
+* Using mixguile::              Using the Scheme interpreter to run and
+                                debug your programs.
+* Using Scheme in mixvm and gmixvm::
+
+Running the program
+
+* Non-interactive mode::        Running your programs non-interactively.
+* Interactive mode::            Running programs interactively.
+* Debugging::                   Commands for debugging your programs.
+
+Using @code{mixguile}
+
+* The mixguile shell::          Using the Scheme MIX virtual machine.
+* Additional functions::        Scheme functions accessing the VM.
+* Defining new functions::      Defining your own Scheme functions.
+* Hook functions::              Using command and break hook functions.
+* Scheme scripts::
+
+Hook functions
+
+* Command hooks::
+* Break hooks::
+
+Emacs tools
+
+* MIXAL mode::                  Editing MIXAL files.
+* GUD integration::             Invoking @code{mixvm} within Emacs.
+
+MIXAL mode
+
+* Basics::                      Editing code, font locking and indentation.
+* Help system::                 Using the interactive help system.
+* Compiling and running::       Invoking compiler and/or virtual machine.
+
+@code{mixasm}, the MIXAL assembler
+
+* Invoking mixasm::
+
+@code{mixvm}, the MIX computer simulator
+
+* Invocation::
+* Commands::                    Commands available in interactive mode.
+* Devices::                     MIX block devices implementation.
+
+Interactive commands
+
+* File commands::               Loading and executing programs.
+* Debug commands::              Debugging programs.
+* State commands::              Inspecting the virtual machine state.
+* Configuration commands::      Changing and storing mixvm settings.
+* Scheme commands::
+
+@code{gmixvm}, the GTK virtual machine
+
+* Invoking gmixvm::
+* MIXVM console::               Using @code{mixvm} commands.
+* MIX virtual machine::         The MIX virtual machine window.
+* MIXAL source view::           Viewing the MIXAL source code.
+* MIX devices view::            Device output.
+* Menu and status bars::        Available menu commands.
+
+@code{mixguile}, the Scheme virtual machine
+
+* Invoking mixguile::           Command line options.
+* Scheme functions reference::  Scheme functions accessing the VM.
+
+Scheme functions reference
+
+* mixvm wrappers::              Functions invoking mixvm commands.
+* Hooks::                       Adding hooks to mixvm commands.
+* Additional VM functions::     Functions accessing the MIX virtual machine.
+
+Copying
+
+* GNU General Public License::
+* GNU Free Documentation License::
+
+@end detailmenu
+@end menu
+
+@include mdk_intro.texi
+@include mdk_ack.texi
+@include mdk_install.texi
+@include mdk_tut.texi
+@include mdk_gstart.texi
+@include mdk_emacs.texi
+@include mdk_mixasm.texi
+@include mdk_mixvm.texi
+@include mdk_gmixvm.texi
+@include mdk_mixguile.texi
+@include mdk_bugs.texi
+@include mdk_copying.texi
+@include mdk_index.texi
+@include mdk_findex.texi
+
+@bye
+
diff --git a/doc/mdk_ack.texi b/doc/mdk_ack.texi
new file mode 100644
index 0000000..807e276
--- /dev/null
+++ b/doc/mdk_ack.texi
@@ -0,0 +1,63 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_ack.texi,v 1.15 2005/09/20 00:26:00 jao Exp $
+
+@node Acknowledgments, Installing MDK, Introduction, Top
+@comment  node-name,  next,  previous,  up
+@unnumbered Acknowledgements
+
+Many people have further contributed to @sc{mdk} by reporting problems,
+suggesting various improvements, or submitting actual code. Here is
+a list of these people. Help me keep it complete and exempt of errors.
+
+@itemize @bullet
+@item Richard Stallman
+suggested various improvements to the documentation and has always
+kept an eye on each @sc{mdk} release.
+
+@item Philip Ellis King
+provided MIXAL test programs pinpointing bugs in the first @sc{mdk}
+release, and useful discussions as well. Philip has also contributed
+with the Emacs port of @code{mixvm} and influenced the @code{gmixvm} GUI
+design with insightful comments and prototypes.
+
+@item Pieter E J Pareit
+is the author of the Emacs MIXAL mode, and has also contributed many
+bug fixes.
+
+@item Michael Scholz
+is the author of the German translation of @sc{mdk}'s user interface.
+
+@item Sergey Poznyakoff
+provided patches to mixlib/mix_scanner.l improving MIXAL compliance.
+
+@item Francesc Xavier Noria
+kindly and thoroughly reviewed the @sc{mdk} documentation, providing
+insightful advice.
+
+@item Nelson H. F. Beebe
+has tested @sc{mdk} in a lot of Unix platforms, suggesting portability
+enhancements to the source code.
+
+@item Agustin Navarro, Ying-Chieh Liao, Adrian Bunk, Baruch Even, and Ronald Cole
+ported @sc{mdk} to different platforms, and created and/or maintain
+packages for it.
+
+@item Jason Uhlenkott, Andrew Hood, Aleix Conchillo, Radu Butnaru, Ruslan Batdalov, WeiZheng and Sascha Wilde
+reported bugs and suggested fixes to them.
+
+@item Eli Bendersky, Milan Bella and Jens Seidel reported bugs on the documentation.
+
+@item Christoph von Nathusius, Stephen Ramsay  and Johan Swanljung
+tested @sc{mdk} on different platforms, and helped fix the configuration
+process in them.
+
+@item @sc{mdk} was inspired by Darius Bacon's
+@uref{http://www.accesscom.com/@/~darius/, MIXAL program}.
+
+@end itemize
+
diff --git a/doc/mdk_bugs.texi b/doc/mdk_bugs.texi
new file mode 100644
index 0000000..1b18064
--- /dev/null
+++ b/doc/mdk_bugs.texi
@@ -0,0 +1,24 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_bugs.texi,v 1.6 2004/08/03 13:23:06 jao Exp $
+
+@node Problems, Copying, mixguile, Top
+@chapter Reporting Bugs
+@cindex bugs
+@cindex problems
+@cindex questions
+@cindex suggestions
+
+If you have any questions, comments or suggestions, please send
+electronic mail to @email{jao@@gnu.org, the author}.
+
+If you find a bug in @sc{mdk}, please send electronic mail to
+@email{bug-mdk@@gnu.org, the @sc{mdk} bug list}.
+
+In your report, please include the version number, which you can find by
+running @w{@samp{mixasm --version}}.  Also include in your message the
+output that the program produced and the output you expected.
diff --git a/doc/mdk_copying.texi b/doc/mdk_copying.texi
new file mode 100644
index 0000000..8aa5e90
--- /dev/null
+++ b/doc/mdk_copying.texi
@@ -0,0 +1,866 @@
+@node Copying, Concept Index, Problems, Top
+@appendix Copying
+
+@menu
+* GNU General Public License::
+* GNU Free Documentation License::
+@end menu
+
+GNU MDK is distributed under the GNU General Public License (GPL) and
+this manual under the GNU Free Documentation License (GFDL).
+
+@node GNU General Public License, GNU Free Documentation License, Copying, Copying
+@appendixsec GNU General Public License
+@cindex GPL, GNU General Public License
+
+@lowersections
+
+@center Version 2, June 1991
+
+@display
+Copyright @copyright{} 1989, 1991 Free Software Foundation, Inc.
+51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+@end display
+
+@unnumberedsec Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software---to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+  Finally, any free program is threatened constantly by software
+patents.  We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary.  To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+@iftex
+@unnumberedsec TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+@end iftex
+@ifinfo
+@center TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+@end ifinfo
+
+@enumerate
+@item
+This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The ``Program'', below,
+refers to any such program or work, and a ``work based on the Program''
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language.  (Hereinafter, translation is included without limitation in
+the term ``modification''.)  Each licensee is addressed as ``you''.
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+@item
+You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+@item
+You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+@enumerate a
+@item
+You must cause the modified files to carry prominent notices
+stating that you changed the files and the date of any change.
+
+@item
+You must cause any work that you distribute or publish, that in
+whole or in part contains or is derived from the Program or any
+part thereof, to be licensed as a whole at no charge to all third
+parties under the terms of this License.
+
+@item
+If the modified program normally reads commands interactively
+when run, you must cause it, when started running for such
+interactive use in the most ordinary way, to print or display an
+announcement including an appropriate copyright notice and a
+notice that there is no warranty (or else, saying that you provide
+a warranty) and that users may redistribute the program under
+these conditions, and telling the user how to view a copy of this
+License.  (Exception: if the Program itself is interactive but
+does not normally print such an announcement, your work based on
+the Program is not required to print an announcement.)
+@end enumerate
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+@item
+You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+@enumerate a
+@item
+Accompany it with the complete corresponding machine-readable
+source code, which must be distributed under the terms of Sections
+1 and 2 above on a medium customarily used for software interchange; or,
+
+@item
+Accompany it with a written offer, valid for at least three
+years, to give any third party, for a charge no more than your
+cost of physically performing source distribution, a complete
+machine-readable copy of the corresponding source code, to be
+distributed under the terms of Sections 1 and 2 above on a medium
+customarily used for software interchange; or,
+
+@item
+Accompany it with the information you received as to the offer
+to distribute corresponding source code.  (This alternative is
+allowed only for noncommercial distribution and only if you
+received the program in object code or executable form with such
+an offer, in accord with Subsection b above.)
+@end enumerate
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+@item
+You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+@item
+You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+@item
+Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+@item
+If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+@item
+If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+@item
+The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and ``any
+later version'', you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+@item
+If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+@iftex
+@heading NO WARRANTY
+@end iftex
+@ifinfo
+@center NO WARRANTY
+@end ifinfo
+
+@item
+BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM ``AS IS'' WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+@item
+IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+@end enumerate
+
+@iftex
+@heading END OF TERMS AND CONDITIONS
+@end iftex
+@ifinfo
+@center END OF TERMS AND CONDITIONS
+@end ifinfo
+
+@page
+@unnumberedsec How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the ``copyright'' line and a pointer to where the full notice is found.
+
+@smallexample
+@var{one line to give the program's name and an idea of what it does.}
+Copyright (C) 19@var{yy}  @var{name of author}
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+@end smallexample
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+@smallexample
+Gnomovision version 69, Copyright (C) 19@var{yy} @var{name of author}
+Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
+type `show w'.  This is free software, and you are welcome
+to redistribute it under certain conditions; type `show c'
+for details.
+@end smallexample
+
+The hypothetical commands @samp{show w} and @samp{show c} should show
+the appropriate parts of the General Public License.  Of course, the
+commands you use may be called something other than @samp{show w} and
+@samp{show c}; they could even be mouse-clicks or menu items---whatever
+suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a ``copyright disclaimer'' for the program, if
+necessary.  Here is a sample; alter the names:
+
+@smallexample
+@group
+Yoyodyne, Inc., hereby disclaims all copyright
+interest in the program `Gnomovision'
+(which makes passes at compilers) written
+by James Hacker.
+
+@var{signature of Ty Coon}, 1 April 1989
+Ty Coon, President of Vice
+@end group
+@end smallexample
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Library General
+Public License instead of this License.
+
+@raisesections
+
+
+
+@node GNU Free Documentation License
+@appendixsec GNU Free Documentation License
+
+@cindex FDL, GNU Free Documentation License
+@center Version 1.2, November 2002
+
+@display
+Copyright @copyright{} 2000,2001,2002 Free Software Foundation, Inc.
+51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
+
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+@end display
+
+@enumerate 0
+@item
+PREAMBLE
+
+The purpose of this License is to make a manual, textbook, or other
+functional and useful document @dfn{free} in the sense of freedom: to
+assure everyone the effective freedom to copy and redistribute it,
+with or without modifying it, either commercially or noncommercially.
+Secondarily, this License preserves for the author and publisher a way
+to get credit for their work, while not being considered responsible
+for modifications made by others.
+
+This License is a kind of ``copyleft'', which means that derivative
+works of the document must themselves be free in the same sense.  It
+complements the GNU General Public License, which is a copyleft
+license designed for free software.
+
+We have designed this License in order to use it for manuals for free
+software, because free software needs free documentation: a free
+program should come with manuals providing the same freedoms that the
+software does.  But this License is not limited to software manuals;
+it can be used for any textual work, regardless of subject matter or
+whether it is published as a printed book.  We recommend this License
+principally for works whose purpose is instruction or reference.
+
+@item
+APPLICABILITY AND DEFINITIONS
+
+This License applies to any manual or other work, in any medium, that
+contains a notice placed by the copyright holder saying it can be
+distributed under the terms of this License.  Such a notice grants a
+world-wide, royalty-free license, unlimited in duration, to use that
+work under the conditions stated herein.  The ``Document'', below,
+refers to any such manual or work.  Any member of the public is a
+licensee, and is addressed as ``you''.  You accept the license if you
+copy, modify or distribute the work in a way requiring permission
+under copyright law.
+
+A ``Modified Version'' of the Document means any work containing the
+Document or a portion of it, either copied verbatim, or with
+modifications and/or translated into another language.
+
+A ``Secondary Section'' is a named appendix or a front-matter section
+of the Document that deals exclusively with the relationship of the
+publishers or authors of the Document to the Document's overall
+subject (or to related matters) and contains nothing that could fall
+directly within that overall subject.  (Thus, if the Document is in
+part a textbook of mathematics, a Secondary Section may not explain
+any mathematics.)  The relationship could be a matter of historical
+connection with the subject or with related matters, or of legal,
+commercial, philosophical, ethical or political position regarding
+them.
+
+The ``Invariant Sections'' are certain Secondary Sections whose titles
+are designated, as being those of Invariant Sections, in the notice
+that says that the Document is released under this License.  If a
+section does not fit the above definition of Secondary then it is not
+allowed to be designated as Invariant.  The Document may contain zero
+Invariant Sections.  If the Document does not identify any Invariant
+Sections then there are none.
+
+The ``Cover Texts'' are certain short passages of text that are listed,
+as Front-Cover Texts or Back-Cover Texts, in the notice that says that
+the Document is released under this License.  A Front-Cover Text may
+be at most 5 words, and a Back-Cover Text may be at most 25 words.
+
+A ``Transparent'' copy of the Document means a machine-readable copy,
+represented in a format whose specification is available to the
+general public, that is suitable for revising the document
+straightforwardly with generic text editors or (for images composed of
+pixels) generic paint programs or (for drawings) some widely available
+drawing editor, and that is suitable for input to text formatters or
+for automatic translation to a variety of formats suitable for input
+to text formatters.  A copy made in an otherwise Transparent file
+format whose markup, or absence of markup, has been arranged to thwart
+or discourage subsequent modification by readers is not Transparent.
+An image format is not Transparent if used for any substantial amount
+of text.  A copy that is not ``Transparent'' is called ``Opaque''.
+
+Examples of suitable formats for Transparent copies include plain
+@sc{ascii} without markup, Texinfo input format, La@TeX{} input
+format, @acronym{SGML} or @acronym{XML} using a publicly available
+@acronym{DTD}, and standard-conforming simple @acronym{HTML},
+PostScript or @acronym{PDF} designed for human modification.  Examples
+of transparent image formats include @acronym{PNG}, @acronym{XCF} and
+@acronym{JPG}.  Opaque formats include proprietary formats that can be
+read and edited only by proprietary word processors, @acronym{SGML} or
+@acronym{XML} for which the @acronym{DTD} and/or processing tools are
+not generally available, and the machine-generated @acronym{HTML},
+PostScript or @acronym{PDF} produced by some word processors for
+output purposes only.
+
+The ``Title Page'' means, for a printed book, the title page itself,
+plus such following pages as are needed to hold, legibly, the material
+this License requires to appear in the title page.  For works in
+formats which do not have any title page as such, ``Title Page'' means
+the text near the most prominent appearance of the work's title,
+preceding the beginning of the body of the text.
+
+A section ``Entitled XYZ'' means a named subunit of the Document whose
+title either is precisely XYZ or contains XYZ in parentheses following
+text that translates XYZ in another language.  (Here XYZ stands for a
+specific section name mentioned below, such as ``Acknowledgements'',
+``Dedications'', ``Endorsements'', or ``History''.)  To ``Preserve the Title''
+of such a section when you modify the Document means that it remains a
+section ``Entitled XYZ'' according to this definition.
+
+The Document may include Warranty Disclaimers next to the notice which
+states that this License applies to the Document.  These Warranty
+Disclaimers are considered to be included by reference in this
+License, but only as regards disclaiming warranties: any other
+implication that these Warranty Disclaimers may have is void and has
+no effect on the meaning of this License.
+
+@item
+VERBATIM COPYING
+
+You may copy and distribute the Document in any medium, either
+commercially or noncommercially, provided that this License, the
+copyright notices, and the license notice saying this License applies
+to the Document are reproduced in all copies, and that you add no other
+conditions whatsoever to those of this License.  You may not use
+technical measures to obstruct or control the reading or further
+copying of the copies you make or distribute.  However, you may accept
+compensation in exchange for copies.  If you distribute a large enough
+number of copies you must also follow the conditions in section 3.
+
+You may also lend copies, under the same conditions stated above, and
+you may publicly display copies.
+
+@item
+COPYING IN QUANTITY
+
+If you publish printed copies (or copies in media that commonly have
+printed covers) of the Document, numbering more than 100, and the
+Document's license notice requires Cover Texts, you must enclose the
+copies in covers that carry, clearly and legibly, all these Cover
+Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
+the back cover.  Both covers must also clearly and legibly identify
+you as the publisher of these copies.  The front cover must present
+the full title with all words of the title equally prominent and
+visible.  You may add other material on the covers in addition.
+Copying with changes limited to the covers, as long as they preserve
+the title of the Document and satisfy these conditions, can be treated
+as verbatim copying in other respects.
+
+If the required texts for either cover are too voluminous to fit
+legibly, you should put the first ones listed (as many as fit
+reasonably) on the actual cover, and continue the rest onto adjacent
+pages.
+
+If you publish or distribute Opaque copies of the Document numbering
+more than 100, you must either include a machine-readable Transparent
+copy along with each Opaque copy, or state in or with each Opaque copy
+a computer-network location from which the general network-using
+public has access to download using public-standard network protocols
+a complete Transparent copy of the Document, free of added material.
+If you use the latter option, you must take reasonably prudent steps,
+when you begin distribution of Opaque copies in quantity, to ensure
+that this Transparent copy will remain thus accessible at the stated
+location until at least one year after the last time you distribute an
+Opaque copy (directly or through your agents or retailers) of that
+edition to the public.
+
+It is requested, but not required, that you contact the authors of the
+Document well before redistributing any large number of copies, to give
+them a chance to provide you with an updated version of the Document.
+
+@item
+MODIFICATIONS
+
+You may copy and distribute a Modified Version of the Document under
+the conditions of sections 2 and 3 above, provided that you release
+the Modified Version under precisely this License, with the Modified
+Version filling the role of the Document, thus licensing distribution
+and modification of the Modified Version to whoever possesses a copy
+of it.  In addition, you must do these things in the Modified Version:
+
+@enumerate A
+@item
+Use in the Title Page (and on the covers, if any) a title distinct
+from that of the Document, and from those of previous versions
+(which should, if there were any, be listed in the History section
+of the Document).  You may use the same title as a previous version
+if the original publisher of that version gives permission.
+
+@item
+List on the Title Page, as authors, one or more persons or entities
+responsible for authorship of the modifications in the Modified
+Version, together with at least five of the principal authors of the
+Document (all of its principal authors, if it has fewer than five),
+unless they release you from this requirement.
+
+@item
+State on the Title page the name of the publisher of the
+Modified Version, as the publisher.
+
+@item
+Preserve all the copyright notices of the Document.
+
+@item
+Add an appropriate copyright notice for your modifications
+adjacent to the other copyright notices.
+
+@item
+Include, immediately after the copyright notices, a license notice
+giving the public permission to use the Modified Version under the
+terms of this License, in the form shown in the Addendum below.
+
+@item
+Preserve in that license notice the full lists of Invariant Sections
+and required Cover Texts given in the Document's license notice.
+
+@item
+Include an unaltered copy of this License.
+
+@item
+Preserve the section Entitled ``History'', Preserve its Title, and add
+to it an item stating at least the title, year, new authors, and
+publisher of the Modified Version as given on the Title Page.  If
+there is no section Entitled ``History'' in the Document, create one
+stating the title, year, authors, and publisher of the Document as
+given on its Title Page, then add an item describing the Modified
+Version as stated in the previous sentence.
+
+@item
+Preserve the network location, if any, given in the Document for
+public access to a Transparent copy of the Document, and likewise
+the network locations given in the Document for previous versions
+it was based on.  These may be placed in the ``History'' section.
+You may omit a network location for a work that was published at
+least four years before the Document itself, or if the original
+publisher of the version it refers to gives permission.
+
+@item
+For any section Entitled ``Acknowledgements'' or ``Dedications'', Preserve
+the Title of the section, and preserve in the section all the
+substance and tone of each of the contributor acknowledgements and/or
+dedications given therein.
+
+@item
+Preserve all the Invariant Sections of the Document,
+unaltered in their text and in their titles.  Section numbers
+or the equivalent are not considered part of the section titles.
+
+@item
+Delete any section Entitled ``Endorsements''.  Such a section
+may not be included in the Modified Version.
+
+@item
+Do not retitle any existing section to be Entitled ``Endorsements'' or
+to conflict in title with any Invariant Section.
+
+@item
+Preserve any Warranty Disclaimers.
+@end enumerate
+
+If the Modified Version includes new front-matter sections or
+appendices that qualify as Secondary Sections and contain no material
+copied from the Document, you may at your option designate some or all
+of these sections as invariant.  To do this, add their titles to the
+list of Invariant Sections in the Modified Version's license notice.
+These titles must be distinct from any other section titles.
+
+You may add a section Entitled ``Endorsements'', provided it contains
+nothing but endorsements of your Modified Version by various
+parties---for example, statements of peer review or that the text has
+been approved by an organization as the authoritative definition of a
+standard.
+
+You may add a passage of up to five words as a Front-Cover Text, and a
+passage of up to 25 words as a Back-Cover Text, to the end of the list
+of Cover Texts in the Modified Version.  Only one passage of
+Front-Cover Text and one of Back-Cover Text may be added by (or
+through arrangements made by) any one entity.  If the Document already
+includes a cover text for the same cover, previously added by you or
+by arrangement made by the same entity you are acting on behalf of,
+you may not add another; but you may replace the old one, on explicit
+permission from the previous publisher that added the old one.
+
+The author(s) and publisher(s) of the Document do not by this License
+give permission to use their names for publicity for or to assert or
+imply endorsement of any Modified Version.
+
+@item
+COMBINING DOCUMENTS
+
+You may combine the Document with other documents released under this
+License, under the terms defined in section 4 above for modified
+versions, provided that you include in the combination all of the
+Invariant Sections of all of the original documents, unmodified, and
+list them all as Invariant Sections of your combined work in its
+license notice, and that you preserve all their Warranty Disclaimers.
+
+The combined work need only contain one copy of this License, and
+multiple identical Invariant Sections may be replaced with a single
+copy.  If there are multiple Invariant Sections with the same name but
+different contents, make the title of each such section unique by
+adding at the end of it, in parentheses, the name of the original
+author or publisher of that section if known, or else a unique number.
+Make the same adjustment to the section titles in the list of
+Invariant Sections in the license notice of the combined work.
+
+In the combination, you must combine any sections Entitled ``History''
+in the various original documents, forming one section Entitled
+``History''; likewise combine any sections Entitled ``Acknowledgements'',
+and any sections Entitled ``Dedications''.  You must delete all
+sections Entitled ``Endorsements.''
+
+@item
+COLLECTIONS OF DOCUMENTS
+
+You may make a collection consisting of the Document and other documents
+released under this License, and replace the individual copies of this
+License in the various documents with a single copy that is included in
+the collection, provided that you follow the rules of this License for
+verbatim copying of each of the documents in all other respects.
+
+You may extract a single document from such a collection, and distribute
+it individually under this License, provided you insert a copy of this
+License into the extracted document, and follow this License in all
+other respects regarding verbatim copying of that document.
+
+@item
+AGGREGATION WITH INDEPENDENT WORKS
+
+A compilation of the Document or its derivatives with other separate
+and independent documents or works, in or on a volume of a storage or
+distribution medium, is called an ``aggregate'' if the copyright
+resulting from the compilation is not used to limit the legal rights
+of the compilation's users beyond what the individual works permit.
+When the Document is included in an aggregate, this License does not
+apply to the other works in the aggregate which are not themselves
+derivative works of the Document.
+
+If the Cover Text requirement of section 3 is applicable to these
+copies of the Document, then if the Document is less than one half of
+the entire aggregate, the Document's Cover Texts may be placed on
+covers that bracket the Document within the aggregate, or the
+electronic equivalent of covers if the Document is in electronic form.
+Otherwise they must appear on printed covers that bracket the whole
+aggregate.
+
+@item
+TRANSLATION
+
+Translation is considered a kind of modification, so you may
+distribute translations of the Document under the terms of section 4.
+Replacing Invariant Sections with translations requires special
+permission from their copyright holders, but you may include
+translations of some or all Invariant Sections in addition to the
+original versions of these Invariant Sections.  You may include a
+translation of this License, and all the license notices in the
+Document, and any Warranty Disclaimers, provided that you also include
+the original English version of this License and the original versions
+of those notices and disclaimers.  In case of a disagreement between
+the translation and the original version of this License or a notice
+or disclaimer, the original version will prevail.
+
+If a section in the Document is Entitled ``Acknowledgements'',
+``Dedications'', or ``History'', the requirement (section 4) to Preserve
+its Title (section 1) will typically require changing the actual
+title.
+
+@item
+TERMINATION
+
+You may not copy, modify, sublicense, or distribute the Document except
+as expressly provided for under this License.  Any other attempt to
+copy, modify, sublicense or distribute the Document is void, and will
+automatically terminate your rights under this License.  However,
+parties who have received copies, or rights, from you under this
+License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+@item
+FUTURE REVISIONS OF THIS LICENSE
+
+The Free Software Foundation may publish new, revised versions
+of the GNU Free Documentation License from time to time.  Such new
+versions will be similar in spirit to the present version, but may
+differ in detail to address new problems or concerns.  See
+@uref{http://www.gnu.org/copyleft/}.
+
+Each version of the License is given a distinguishing version number.
+If the Document specifies that a particular numbered version of this
+License ``or any later version'' applies to it, you have the option of
+following the terms and conditions either of that specified version or
+of any later version that has been published (not as a draft) by the
+Free Software Foundation.  If the Document does not specify a version
+number of this License, you may choose any version ever published (not
+as a draft) by the Free Software Foundation.
+@end enumerate
+
+@page
+@appendixsubsec ADDENDUM: How to use this License for your documents
+
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and
+license notices just after the title page:
+
+@smallexample
+@group
+  Copyright (C)  @var{year}  @var{your name}.
+  Permission is granted to copy, distribute and/or modify this document
+  under the terms of the GNU Free Documentation License, Version 1.2
+  or any later version published by the Free Software Foundation;
+  with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
+  Texts.  A copy of the license is included in the section entitled ``GNU
+  Free Documentation License''.
+@end group
+@end smallexample
+
+If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
+replace the ``with...Texts.'' line with this:
+
+@smallexample
+@group
+    with the Invariant Sections being @var{list their titles}, with
+    the Front-Cover Texts being @var{list}, and with the Back-Cover Texts
+    being @var{list}.
+@end group
+@end smallexample
+
+If you have Invariant Sections without Cover Texts, or some other
+combination of the three, merge those two alternatives to suit the
+situation.
+
+If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of
+free software license, such as the GNU General Public License,
+to permit their use in free software.
+
+@c Local Variables:
+@c ispell-local-pdict: "ispell-dict"
+@c End:
+
diff --git a/doc/mdk_emacs.texi b/doc/mdk_emacs.texi
new file mode 100644
index 0000000..e0c6973
--- /dev/null
+++ b/doc/mdk_emacs.texi
@@ -0,0 +1,136 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@node Emacs tools, mixasm, Getting started, Top
+@chapter Emacs tools
+
+Everyone writing code knows how important a good editor is. Most
+systems already come with Emacs, and excellent programmer's editor.
+@sc{mdk} adds support to Emacs for both writing and debugging MIX
+programs. A major mode for MIXAL source files eases edition of your
+code, while integration with Emacs' debugging interface
+(@acronym{GUD}) lets you use @code{mixvm} without leaving your
+favourite text editor.
+
+This chapter shows how to use the Elisp modules included in @sc{mdk},
+assuming that you have followed the installation instructions in
+@xref{Emacs support}.
+
+@menu
+* MIXAL mode::                  Editing MIXAL files.
+* GUD integration::             Invoking @code{mixvm} within Emacs.
+@end menu
+
+@node MIXAL mode, GUD integration, Emacs tools, Emacs tools
+@section MIXAL mode
+
+The module @file{mixal-mode.el} provides a new mode, mixal-mode, for
+editing MIXAL source files@footnote{mixal-mode has been developed and
+documented by @value{PIETER}}. When everything is installed correctly,
+Emacs will select it as the major mode for editing files with extension
+@code{.mixal}. You can also activate mixal-mode in any buffer
+issuing the Emacs command @code{M-x mixal-mode}.
+
+@menu
+* Basics::                      Editing code, font locking and indentation.
+* Help system::                 Using the interactive help system.
+* Compiling and running::       Invoking compiler and/or virtual machine.
+@end menu
+
+@node Basics, Help system, MIXAL mode, MIXAL mode
+@comment node-name, next, previous, up
+@subsection Basics
+
+The mode for editing mixal source files is inherited from
+fundamental-mode, meaning that all your favorite editing operations
+will still work. If you want a short introduction to Emacs, type
+@kbd{C-h t} inside Emacs to start the tutorial.
+
+Mixal mode adds font locking. If you do not have font locking globally
+enabled, you can turn it on for mixal-mode by placing the following
+line in your @file{.emacs} file:
+
+@lisp
+(add-hook 'mixal-mode-hook 'turn-on-font-lock)
+@end lisp
+
+You can also customize the colors used to colour your mixal code by
+changing the requisite faces. This is the list of faces used by
+mixal-mode:
+
+@itemize
+@item @var{font-lock-comment-face}
+Face to use for comments.
+@item @var{mixal-font-lock-label-face}
+Face to use for label names.
+@item @var{mixal-font-lock-operation-code-face}
+Face to use for operation code names.
+@item @var{mixal-font-lock-assembly-pseudoinstruction-face}
+Face to use for assembly pseudo-instruction names.
+@end itemize
+
+@node Help system, Compiling and running, Basics, MIXAL mode
+@comment node-name, next, previous, up
+@subsection Help system
+
+When coding your program, you will be thinking, looking up
+documentation and editing files. Emacs already helps you with editing
+files, but Emacs can do much more. In particular, looking up
+documentation is one of its strong points. Besides the info system
+(which you are probably already using), mixal-mode defines commands
+for getting particular information about a MIX operation code.
+
+With @kbd{M-x mixal-describe-operation-code} (or its keyboard shortcut
+@kbd{C-h o}) you will get the documentation about a particular MIX
+operation code. Keep in mind that these are not assembly (MIXAL)
+pseudoinstructions. When the @code{point} is around a MIXAL
+pseudoinstruction in your source file, Emacs will recognize it and
+will suggest the right MIX operation code.
+
+@node Compiling and running,  , Help system, MIXAL mode
+@comment node-name, next, previous, up
+@subsection Compiling and running
+
+After you have written your MIXAL program, you'll probably want to
+test it. This can be done with the MIX virtual machine. First you will
+need to compile your code into MIX byte code. This can be done within
+Emacs with the command @kbd{M-x compile} (@kbd{C-c c}). In case of
+compilation errors, you can jump to the offending source code line
+with @kbd{M-x next-error}.
+
+Once the program compiles without errors, you can debug or run
+it. To invoke the debugger, use @kbd{M-x mixal-debug} (@kbd{C-c d}).
+Emacs will open a @code{GUD} buffer where you can
+use the debugging commands described in @xref{mixvm}.
+
+If you just want to execute the program, you can do so with @kbd{M-x
+mixal-run} (@kbd{C-c r}). This will invoke mixvm,
+execute the program and show its output in a separate buffer.
+
+@node GUD integration,  , MIXAL mode, Emacs tools
+@section GUD integration
+
+If you are an Emacs user and write your MIXAL programs using this
+editor, you will find the elisp program @file{mixvm.el} quite
+useful@footnote{@file{mixvm.el} has been kindly contributed by
+@value{PHILIP}. @file{mixvm.el} is based on a study of gdb, perldb, and
+pdb as found in @file{gud.el}, and @file{rubydb3x.el} distributed with
+the source code to the Ruby language.}. @file{mixvm.el} allows running
+the MIX virtual machine @code{mixvm} (@pxref{mixvm}) inside an Emacs
+@acronym{GUD} buffer, while visiting the MIXAL source file in another
+buffer.
+
+After installing @file{mixvm.el} (@pxref{Emacs support}), you can
+initiate an @sc{mdk}/@acronym{GUD} session inside Emacs with the command
+
+@example
+M-x mixvm
+@end example
+
+@noindent
+and you will have a @code{mixvm} prompt inside a newly created
+@acronym{GUD} buffer. @acronym{GUD} will reflect the current line in the
+corresponding source file buffer.
diff --git a/doc/mdk_findex.texi b/doc/mdk_findex.texi
new file mode 100644
index 0000000..24a269f
--- /dev/null
+++ b/doc/mdk_findex.texi
@@ -0,0 +1,11 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_findex.texi,v 1.3 2004/08/03 13:23:06 jao Exp $
+
+@node Instructions and commands, , Concept Index, Top
+@unnumbered Instructions and commands
+@printindex fn
diff --git a/doc/mdk_gmixvm.texi b/doc/mdk_gmixvm.texi
new file mode 100644
index 0000000..bddb362
--- /dev/null
+++ b/doc/mdk_gmixvm.texi
@@ -0,0 +1,394 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_gmixvm.texi,v 1.18 2004/08/03 13:23:06 jao Exp $
+
+@node gmixvm, mixguile, mixvm, Top
+@comment  node-name,  next,  previous,  up
+@chapter @code{gmixvm}, the GTK virtual machine
+@cindex @code{gmixvm}
+@cindex GUI
+@cindex GTK+
+
+This chapter describes the graphical MIX virtual machine emulator
+shipped with @sc{mdk}. In addition to having all the command-oriented
+functionalities of the other virtual machines (@code{mixvm} and
+@code{mixguile}), @code{gmixvm} offers you a graphical interface
+displaying the status of the virtual machine, the source code of the the
+downloaded programs and the contents of the MIX devices.
+
+@menu
+* Invoking gmixvm::
+* MIXVM console::               Using @code{mixvm} commands.
+* MIX virtual machine::         The MIX virtual machine window.
+* MIXAL source view::           Viewing the MIXAL source code.
+* MIX devices view::            Device output.
+* Menu and status bars::        Available menu commands.
+@end menu
+
+@node Invoking gmixvm, MIXVM console, gmixvm, gmixvm
+@comment  node-name,  next,  previous,  up
+@section Invoking @code{gmixvm}
+
+If you have built @sc{mdk} with GTK+ support (@pxref{Installing MDK}), a
+graphical front-end for the MIX virtual machine will be available in
+your system. You can invoke it by typing
+
+@example
+gmixvm [-vhuq] [--version] [--help] [--usage] [--noinit]
+@end example
+@noindent
+at your command prompt, where the options have the following meanings:
+
+@defopt -v
+@defoptx --version
+Prints version and copyleft information and exits.
+@end defopt
+
+@defopt -h
+@defoptx --help
+@defoptx -u
+@defoptx --usage
+Prints a summary of available options and exits.
+@end defopt
+
+@defopt -q
+@defoptx --noinit
+Do not load the Guile initialisation file @code{~/.mdk/mixguile.scm} at
+startup. This file contains any local Scheme code to be executed by the
+embedded Guile interpreter at startup (@pxref{Using Scheme in mixvm and
+gmixvm}).
+@end defopt
+
+Typing @code{gmixvm} or @code{gmixvm -q} at your command prompt, the
+main window will appear, offering you a graphical interface to run and
+debug your MIX programs.
+
+@ifinfo
+@image{img/ss_mix, 400pt}
+@end ifinfo
+
+@ifhtml
+@image{../img/ss_mix, 400pt}
+@end ifhtml
+
+Apart from the menu and status bars, we can distinguish two zones (or
+halves) in this main window. In the upper half of @code{gmixvm}'s main
+window there is a notebook with three pages, namely,
+
+@itemize
+@item
+a MIX virtual machine view, which shows you the registers, flags, memory
+contents and time statistics of the virtual machine;
+@item
+a MIXAL source view, which shows the MIXAL file and lets you manage
+breakpoints;
+@item
+a Devices view, which shows you the output to character based MIX block
+devices.
+@end itemize
+
+@noindent
+These three windows can be detached from the notebook, using either
+the penultimate toolbar button (which detachs the currently visible
+notebook page) or the menu entries under @code{@w{View->Detached windows}}.
+
+@ifhtml
+Here is an screenshot showing how @code{gmixvm} looks like when running
+with a couple of detached windows:
+
+@image{../img/ss_split, 420pt}
+
+@end ifhtml
+
+On the other hand, the main window's lower half presents you a
+@code{mixvm} command prompt and a logging area where results of the
+issued commands are presented. These widgets implement a @code{mixvm}
+console which offers almost the same functionality as its
+@acronym{CLI} counterpart.
+
+When @code{gmixvm} is run, it creates a directory named @file{.mdk} in
+your home directory (if it does not already exist). The @file{.mdk}
+directory contains the program settings, the device files used by your
+MIX programs (@pxref{Devices}), and a command history file.
+
+The following sections describe the above mentioned components of
+@code{gmixvm}.
+
+@node MIXVM console, MIX virtual machine, Invoking gmixvm, gmixvm
+@comment  node-name,  next,  previous,  up
+@section MIXVM console
+
+In the lower half of the @code{gmixvm} main window, you will find a
+command text entry and, above it, an echo area. These widgets offer you
+the same functionality as its @acronym{CLI} counterpart, @code{mixvm}
+(@pxref{mixvm}). You can issue almost all @code{mixmv} commands at the
+@code{gmixvm}'s command prompt in order to manipulate the MIX virtual
+machine. Please refer to @xref{mixvm}, for a description of these
+commands, and to @xref{Getting started}, for a tutorial on using the MIX
+virtual machine. The command prompt offers command line completion for
+partially typed commands using the @key{TAB} key; e.g., if you type
+
+@example
+lo @key{TAB}
+@end example
+@noindent
+the command is automatically completed to @code{load}. If multiple
+completions are available, they will be shown in the echo area. Thus,
+typing
+
+@example
+p @key{TAB}
+@end example
+@noindent
+will produce the following output on the echo area:
+
+@example
+Completions:
+pc     psym     preg     pflags     pall
+pmem
+@end example
+@noindent
+which lists all the available commands starting with @code{p}. In
+addition, the command prompt maintains a history of typed commands,
+which can be recovered using the arrow up and down keys. As mentioned
+above, a file containing previous sessions' commands is stored in the
+configuration directory @file{~/.mdk}, and reloaded every time you start
+@code{gmixvm}.
+
+You can change the font used to display the issued commands and the
+messages in the echo area using the @code{@w{Settings->Change font->Command
+prompt}} and @code{@w{Settings->Change font->Command log}} menu commands.
+
+@node MIX virtual machine, MIXAL source view, MIXVM console, gmixvm
+@comment  node-name,  next,  previous,  up
+@section MIX virtual machine
+
+The first notebook's page displays the current status of the virtual
+machine. There you can find the registers' contents, the value of the
+comparison and overflow flags, the location pointer, a list with all MIX
+memory cells and their contents, and the time statistics (including
+total uptime, elapsed time since the last run command and total
+execution time for the currently loaded MIX program).
+
+If you click any register entry, you will be prompted for a new register's
+contents.
+
+@ifhtml
+The next figure shows the enter word dialog.
+
+@image{../img/ss_worddlg, 250pt}
+
+@end ifhtml
+
+In the same manner, click on any address of the memory cells list to be
+prompted for the new contents of the clicked cell. If you click the
+address column's title, a dialog asking you for a memory address will
+appear; if you introduce a valid address, this will be the first cell
+displayed in the scrollable list after you click the OK button.
+
+The register contents are shown as a list of MIX bytes plus sign. If you
+place the mouse pointer over any of them, the decimal value of this MIX
+word will appear inside a tooltip.
+
+You can change the font used to display the MIX virtual machine contents
+using the @code{@w{Settings->Change font->MIX}} menu command.
+
+@node MIXAL source view, MIX devices view, MIX virtual machine, gmixvm
+@comment  node-name,  next,  previous,  up
+@section MIXAL source view
+
+The second notebook's page, dubbed Source, shows you the MIXAL source of
+the currently loaded MIX file.
+
+@ifhtml
+@image{../img/ss_mixal, 400pt}
+@end ifhtml
+
+The information is presented in four columns. The first column
+displays little icons showing the current program pointer and any set
+breakpoints. The second and third columns show the address and memory
+contents of the compiled MIX instruction, while the last one displays
+its corresponding MIXAL representation, together with the source file
+line number. You can set/unset breakpoints by clicking on any line
+that has an associated memory address.
+
+You can change the font used to display the MIXAL source code
+using the @code{@w{Settings->Change font->MIXAL}} menu command.
+
+@node MIX devices view, Menu and status bars, MIXAL source view, gmixvm
+@comment  node-name,  next,  previous,  up
+@section MIX devices view
+
+The last notebook page, dubbed Devices, shows you the output/input
+to/from MIX block devices (the console, line printer, paper tape,
+disks, card and tapes @pxref{Devices}) produced by the running
+program.
+
+@ifhtml
+
+@image{../img/ss_devices, 400pt}
+
+@end ifhtml
+
+Input device contents is read from files located in the @file{~/.mdk}
+directory, and the output is also written to files at the same
+location. Note that device tabs will appear as they are used by the MIX
+program being run, and that loading a new MIX program will close all
+previously open devices.
+
+The input/output for binary block devices (tapes and disks) is a list
+of MIX words, which can be displayed either in decimal or word format
+(e.g. @w{- 67} or @w{- 00 00 00 01 03}). The format used by
+@code{gmixvm} can be configured using the @code{@w{Settings->Device output}}
+menu command for each binary device.
+
+You can change the font used to display the devices content
+using the @code{@w{Settings->Change font->Devices}} menu command.
+
+@node Menu and status bars,  , MIX devices view, gmixvm
+@comment  node-name,  next,  previous,  up
+@section Menu and status bars
+
+The menu bar gives you access to the following commands:
+
+@deffn File Load...
+Opens a file dialog that lets you specify a binary MIX file to be loaded
+in the virtual machine's memory. It is equivalent to the @code{mixvm}'s
+@code{load} command (@pxref{File commands}).
+@end deffn
+
+@deffn File Edit...
+Opens a file dialog that lets your specify a MIXAL source file to be
+edited. It is equivalent to the @code{mixvm}'s @code{edit} command
+(@pxref{File commands}). The program used for editing can be specified
+using the menu entry @code{@w{Settings->External programs}}, or using the
+@code{mixvm} command @code{sedit}.
+@end deffn
+
+@deffn File Compile...
+Opens a file dialog that lets your specify a MIXAL source file to be
+compiled. It is equivalent to the @code{mixvm}'s @code{compile} command
+(@pxref{File commands}). The command used for compiling can be specified
+using the menu entry @code{@w{Settings->External programs}}, or using the
+@code{mixvm} command @code{sasm}.
+@end deffn
+
+@deffn File Exit
+Exits the application.
+@end deffn
+
+@deffn Debug Run
+Runs the currently loaded MIX program, up to the next breakpoint. It is
+equivalent to the @code{mixvm}'s @code{run} command (@pxref{Debug
+commands}).
+@end deffn
+
+@deffn Debug Next
+Executes the next MIX instruction. It is equivalent to the
+@code{mixvm}'s @code{next} command (@pxref{Debug commands}).
+@end deffn
+
+@deffn Debug @w{Clear breakpoints}
+Clears all currently set breakpoints. It is equivalent to the
+@code{mixvm}'s @code{cabp} command.
+@end deffn
+
+@deffn Debug Symbols...
+Opens a dialog showing the list of symbols defined in the currently
+loaded MIX program. The font used to display this list can be
+customised using the meny entry @code{@w{Settings->Change font->Symbol
+list}}.
+
+@ifhtml
+
+@image{../img/ss_symbols, 250pt}
+
+@end ifhtml
+
+@end deffn
+
+@deffn View @w{Toolbar(s)}
+Toggles the toolbar(s) in the @code{gmixvm} window(s) (when notebook
+pages are detached, each one has its own toolbar).
+@end deffn
+
+@deffn View @w{Detached windows} @w{Virtual machine}
+@deffnx View @w{Detached windows} Source
+@deffnx View @w{Detached windows} Devices
+
+These toggles let you detach (or re-attach) the corresponding notebook
+page.
+
+@end deffn
+
+@deffn Settings @w{Change font}
+Lets you change the font used in the various @code{gmixv} widgets
+(i.e. commad prompt, command log, Virtual machine, Source, Devices and
+Symbol list). There is also an entry (@code{All}) to change all fonts
+at once.
+@end deffn
+
+@deffn Settings @w{Device output...}
+Opens a dialog that lets you specify which format shall be used to show
+the contents of MIX binary block devices.
+
+@ifhtml
+@image{../img/ss_devform, 250pt}
+@end ifhtml
+
+The available formats are decimal (e.g. @w{-1234}) and MIX word
+(e.g. @w{- 00 00 00 19 18}).
+@end deffn
+
+@deffn Settings @w{Devices dir...}
+Opens a dialog that lets you choose where the MIX device files will be
+stored (@file{~/.mdk} is the default location).
+
+@ifhtml
+@image{../img/ss_devdir, 250pt}
+@end ifhtml
+
+You can also specify the devices directory using the @code{mixvm}
+command @code{sddir} (@pxref{Configuration commands}).
+
+@end deffn
+
+@deffn Settings @w{External programs...}
+This menu command opens a dialog that lets you specify the commands used
+for editing and compiling MIXAL source files.
+
+@ifhtml
+@image{../img/ss_extprog, 250pt}
+@end ifhtml
+
+The commands are specified as template strings, where the control
+substring @code{%s} will be substituted by the actual file name. Thus,
+if you want to edit programs using @code{vi} running in an @code{xterm},
+you must enter the command template @code{@w{xterm -e vi %s}} in the
+corresponding dialog entry. These settings can also be changed using the
+@code{mixvm} commands @code{sedit} and @code{sasm} (@pxref{Configuration
+commands}).
+@end deffn
+
+
+@deffn Settings Save
+Saves the current settings.
+@end deffn
+
+@deffn Settings @w{Save on exit}
+Mark this checkbox if you want @code{gmixvm} to save its settings
+every time you quit the program.
+@end deffn
+
+@deffn Help About...
+Shows information about @code{gmixvm}'s version and copyright.
+@end deffn
+
+On the other hand, the status bar displays the name of the last loaded
+MIX file. In addition, when the mouse pointer is over a MIXAL source
+file line that contains symbols, a list of these symbols with their
+values will appear in the status bar.
diff --git a/doc/mdk_gstart.texi b/doc/mdk_gstart.texi
new file mode 100644
index 0000000..9eab3f6
--- /dev/null
+++ b/doc/mdk_gstart.texi
@@ -0,0 +1,1058 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2002, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_gstart.texi,v 1.17 2004/08/01 21:43:29 jao Exp $
+
+@node Getting started, Emacs tools, MIX and MIXAL tutorial, Top
+@chapter Getting started
+@cindex tutorial
+
+In this chapter, you will find a sample code-compile-run-debug session
+using the @sc{mdk} utilities. Familiarity with the MIX mythical computer
+and its assembly language MIXAL (as described in Knuth's TAOCP) is
+assumed; for a compact reminder, see @ref{MIX and MIXAL tutorial}.
+
+@menu
+* Writing a source file::       A sample MIXAL source file.
+* Compiling::                   Using @code{mixasm} to compile source
+                                files into binary format.
+* Running the program::         Running and debugging your programs.
+* Using mixguile::              Using the Scheme interpreter to run and
+                                debug your programs.
+* Using Scheme in mixvm and gmixvm::
+@end menu
+
+@node Writing a source file, Compiling, Getting started, Getting started
+@section Writing a source file
+@cindex MIXAL
+@cindex source file
+@cindex .mixal file
+
+MIXAL programs can be written as ASCII files with your editor of choice.
+Here you have the mandatory @emph{hello world} as written in the MIXAL
+assembly language:
+
+@example
+*                                                        (1)
+* hello.mixal: say 'hello world' in MIXAL                (2)
+*                                                        (3)
+* label ins    operand     comment                       (4)
+TERM    EQU    19          the MIX console device number (5)
+        ORIG   1000        start address                 (6)
+START   OUT    MSG(TERM)   output data at address MSG    (7)
+        HLT                halt execution                (8)
+MSG     ALF    "MIXAL"                                   (9)
+        ALF    " HELL"                                   (10)
+        ALF    "O WOR"                                   (11)
+        ALF    "LD   "                                   (12)
+        END    START       end of the program            (13)
+@end example
+
+@noindent MIXAL source files should have the extension @file{.mixal}
+when used with the @sc{mdk} utilities. As you can see in the above
+sample, each line in a MIXAL file can be divided into four fields
+separated by an arbitrary amount of whitespace characters (blanks and or
+tabs). While in Knuth's definition of MIXAL each field must start at a
+fixed pre-defined column number, the @sc{mdk} assembler loosens this
+requirement and lets you format the file as you see fit. The only
+restrictions retained are for comment lines (like 1-4) which must begin
+with an asterisk (*) placed at column 1, and for the label field (see
+below) which, if present, must also start at column 1. The four fields
+in each non-comment line are:
+
+@itemize @minus
+@item
+an optional label, which either refers to the current memory address (as
+@code{START} and @code{MSG} in lines 7 and 9) or a defined symbol
+(@code{TERM}) (if present, the label must always start at the first
+column in its line, for the first whitespace in the line maks the
+beginning of the second field),
+@item
+an operation mnemonic, which can represent either a MIX instruction
+(@code{OUT} and @code{HLT} in lines 7 and 8 above), or an assembly
+pseudoinstruction (e.g., the @code{ORIG} pseudoinstruction in line
+6@footnote{If an @code{ORIG} directive is not used, the program will
+be loaded by the virtual machine at address 0. @code{ORIG} allows
+allocating the executable code where you see fit.}.
+@item
+an optional operand for the (pseudo)instruction, and
+@item
+an optional free text comment.
+@end itemize
+
+@noindent Lines 9-12 of the @file{hello.mixal} file above also show the
+second (and last) difference between Knuth's MIXAL definition and ours:
+the operand of the @code{ALF} pseudoinstruction (a word of five
+characters) must be quoted using ""@footnote{In Knuth's definition,
+the operand always starts at a fixed column number, and the use of
+quotation is therefore unnecessary. As @code{mixasm} releases this
+requirement, marking the beginning and end of the @code{ALF} operand
+disambiguates the parser's recognition of this operand when it includes
+blanks. Note that double-quotes (") are not part of the MIX character
+set, and, therefore, no escape characters are needed within
+@code{ALF}'s operands.}.
+
+The workings of this sample program should be straightforward if you are
+familiar with MIXAL. See TAOCP vol. 1 for a thorough definition or
+@ref{MIX and MIXAL tutorial}, for a tutorial.
+
+@node Compiling, Running the program, Writing a source file, Getting started
+@section Compiling
+@cindex compiling
+@cindex binary programs
+@cindex virtual machine
+@cindex assembler
+@cindex @code{mixasm}
+
+Three simulators of the MIX computer, called @code{mixvm}, @code{gmixvm}
+and @code{mixguile}, are included in the @sc{mdk} tools. They are able to
+run binary files containing MIX instructions written in their binary
+representation. You can translate MIXAL source files into this binary
+form using @code{mixasm}, the MIXAL assembler. So, in order to compile
+the @file{hello.mixal} file, you can type the following command at your
+shell prompt:
+
+@example
+mixasm hello @key{RET}
+@end example
+
+@cindex .mix file
+
+If the source file contains no errors, this will produce a binary file
+called @file{hello.mix} which can be loaded and run by the MIX virtual
+machine. Unless the @code{mixasm} option @code{-O} is provided, the
+assembler will include debug information in the executable file (for a
+complete description of all the compilation options, see
+@ref{mixasm}). Now, your are ready to run your first MIX program, as
+described in the following section.
+
+
+@node Running the program, Using mixguile, Compiling, Getting started
+@section Running the program
+@cindex @code{mixvm}
+@cindex non-interactive mode
+@cindex interactive mode
+
+MIX is a mythical computer, so it is no use ordering it from your
+favorite hardware provider. @sc{mdk} provides three software simulators of
+the computer, though. They are
+
+@itemize @bullet
+@item
+@code{mixvm}, a command line oriented simulator,
+@item
+@code{gmixvm}, a GTK based graphical interface to @code{mixvm}, and
+@item
+@code{mixguile}, a Guile shell with a built-in MIX simulator.
+@end itemize
+
+All three simulators accept the same set of user commands, but offer a
+different user interface, as noted above. In this section we shall
+describe some of these commands, and show you how to use them from
+@code{mixvm}'s command line. You can use them as well at @code{gmixvm}'s
+command prompt (@pxref{gmixvm}), or using the built-in Scheme primitives
+of @code{mixguile} (@pxref{Using mixguile}).
+
+Using the MIX simulators, you can run your MIXAL programs, after
+compiling them with @code{mixasm} into binary @file{.mix}
+files. @code{mixvm} can be used either in @dfn{interactive} or
+@dfn{non-interactive} mode. In the second case, @code{mixvm} will load
+your program into memory, execute it (producing any output due to
+MIXAL @code{OUT} instructions present in the program), and exit when
+it encounters a @code{HLT} instruction. In interactive mode, you will
+enter a shell prompt which allows you issuing commands to the running
+virtual machine. This commands will permit you to load, run and debug
+programs, as well as to inspect the MIX computer state (register
+contents, memory cells contents and so on).
+
+@menu
+* Non-interactive mode::        Running your programs non-interactively.
+* Interactive mode::            Running programs interactively.
+* Debugging::                   Commands for debugging your programs.
+@end menu
+
+@node Non-interactive mode, Interactive mode, Running the program, Running the program
+@comment  node-name,  next,  previous,  up
+@subsection Non-interactive mode
+@cindex non-interactive mode
+
+To make @code{mixvm} work in non-interactive mode, use the @code{-r}
+flag. Thus, to run our @file{hello.mix} program, simply type
+
+@example
+mixvm -r hello @key{RET}
+@end example
+
+@noindent at your command prompt, and you will get the following output:
+
+@example
+MIXAL HELLO WORLD
+@end example
+
+@noindent Since our hello world program uses MIX's device number 19 as
+its output device (@pxref{Writing a source file}), the output is
+redirected to the shell's standard output. Had you used any other MIX
+output devices (disks, drums, line printer, etc.), @code{mixvm} would
+have created a file named after the device used (e.g. @file{disk4.dev})
+and written its output there@footnote{The device files are stored, by
+default, in a directory called @file{.mdk}, which is created in your
+home directory the first time @code{mixvm} is run. You can change this
+default directory using the command @code{devdir} when running
+@code{mixvm} in interactive mode (@pxref{Configuration commands})}.
+
+The virtual machine can also report the execution time of the program,
+according to the (virtual) time spent in each of the binary instructions
+(@pxref{Execution times}). Printing of execution time statistics is
+activated with the @code{-t} flag; running
+
+@example
+mixvm -t -r hello @key{RET}
+@end example
+
+@noindent
+produces the following output:
+
+@example
+MIXAL HELLO WORLD
+** Execution time: 11
+@end example
+
+Sometimes, you will prefer to store the results of your program in MIX
+registers rather than writing them to a device. In such cases,
+@code{mixvm}'s @code{-d} flag is your friend: it makes @code{mixvm} to
+dump the contents of its registers and flags after executing the loaded
+program. For instance, typing the following command at your shell's
+prompt
+
+@example
+mixvm -d -r hello
+@end example
+
+@noindent you will obtain the following output:
+
+@example
+MIXAL HELLO WORLD
+rA: + 00 00 00 00 00 (0000000000)
+rX: + 00 00 00 00 00 (0000000000)
+rJ: + 00 00 (0000)
+rI1: + 00 00 (0000)     rI2: + 00 00 (0000)
+rI3: + 00 00 (0000)     rI4: + 00 00 (0000)
+rI5: + 00 00 (0000)     rI6: + 00 00 (0000)
+Overflow: F
+Cmp: E
+@end example
+
+@noindent which, in addition to the program's outputs and execution
+time, gives you the contents of the MIX registers and the values of the
+overflow toggle and comparison flag (admittedly, rather uninteresting in
+our sample).
+
+As you can see, running programs non-interactively has many
+limitations. You cannot peek the virtual machine's memory contents, not
+to mention stepping through your program's instructions or setting
+breakpoints@footnote{The @code{mixguile} program allows you to execute
+arbitrary combinations of @code{mixvm} commands (using Scheme)
+non-interactively. @xref{Scheme scripts}.}. Enter interactive mode.
+
+@node Interactive mode, Debugging, Non-interactive mode, Running the program
+@comment  node-name,  next,  previous,  up
+@subsection Interactive mode
+@cindex interactive mode
+
+To enter the MIX virtual machine interactive mode, simply type
+
+@example
+mixvm @key{RET}
+@end example
+
+@noindent at your shell command prompt. This command enters the
+@code{mixvm} command shell. You will be presented the following command
+prompt:
+
+@example
+MIX >
+@end example
+
+@noindent The virtual machine is initialised and ready to accept your
+commands. The @code{mixvm} command shell uses GNU's readline, so that
+you have at your disposal command completion (using @key{TAB}) and
+history functionality, as well as other line editing shortcuts common to
+all utilities using this library (for a complete description of
+readline's line editing usage, see @ref{Command Line
+Editing,,,Readline}.)
+
+@cindex @code{load}
+Usually, the first thing you will want to do is loading a compiled MIX
+program into memory. This is acomplished by the @code{load} command,
+which takes as an argument the name of the @file{.mix} file to be
+loaded. Thus, typing
+
+@example
+MIX > load hello @key{RET}
+Program loaded. Start address: 3000
+MIX >
+@end example
+
+@noindent will load @file{hello.mix} into the virtual machine's memory
+and set the program counter to the address of the first instruction. You
+can obtain the contents of the program counter using the command
+@code{pc}:
+
+@cindex @code{pc}
+@example
+MIX > pc
+Current address: 3000
+MIX >
+@end example
+
+@cindex @code{run}
+After loading it, you are ready to run the program, using, as you surely
+have guessed, the @code{run} command:
+
+@example
+MIX > run
+Running ...
+MIXAL HELLO WORLD
+... done
+Elapsed time: 11 /Total program time: 11 (Total uptime: 11)
+MIX >
+@end example
+
+@noindent Note that now the timing statistics are richer. You obtain the
+elapsed execution time (i.e., the time spent executing instructions
+since the last breakpoint), the total execution time for the program up
+to now (which in our case coincides with the elapsed time, since there
+were no breakpoints), and the total uptime for the virtual machine (you
+can load and run more than one program in the same
+session)@footnote{Printing of timing statistics can be disabled using
+the command @code{timing} (@pxref{Configuration commands}).}. After
+running the program, the program counter will point to the address after
+the one containing the @code{HLT} instruction. In our case, asking the
+value of the program counter after executing the program will give us
+
+@example
+MIX > pc
+Current address: 3002
+MIX >
+@end example
+
+@cindex @code{pmem}
+@noindent You can check the contents of a memory cell giving its address
+as an argument of the command @code{pmem}, like this
+
+@example
+MIX > pmem 3001
+3001: + 00 00 00 02 05 (0000000133)
+MIX >
+@end example
+
+@noindent
+and convince yourself that address 3001 contains the binary
+representation of the instruction @code{HLT}. An address range of the
+form FROM-TO can also be used as the argument of @code{pmem}:
+
+@example
+MIX > pmem 3000-3006
+3000: + 46 58 00 19 37 (0786957541)
+3001: + 00 00 00 02 05 (0000000133)
+3002: + 14 09 27 01 13 (0237350989)
+3003: + 00 08 05 13 13 (0002118477)
+3004: + 16 00 26 16 19 (0268542995)
+3005: + 13 04 00 00 00 (0219152384)
+3006: + 00 00 00 00 00 (0000000000)
+MIX >
+@end example
+
+@cindex @code{preg}
+@noindent
+In a similar manner, you can look at the contents of the MIX registers
+and flags. For instance, to ask for the contents of the A register you
+can type
+
+@example
+MIX > preg A
+rA: + 00 00 00 00 00 (0000000000)
+MIX >
+@end example
+
+@cindex @code{help}
+@noindent
+Use the comand @code{help} to obtain a list of all available commands,
+and @code{help COMMAND} for help on a specific command, e.g.
+
+@example
+MIX > help run
+run             Run loaded or given MIX code file. Usage: run [FILENAME]
+MIX >
+@end example
+
+@noindent
+For a complete list of commands available at the MIX propmt,
+@xref{mixvm}. In the following subsection, you will find a quick tour
+over commands useful for debugging your programs.
+
+@node Debugging,  , Interactive mode, Running the program
+@comment  node-name,  next,  previous,  up
+@subsection Debugging commands
+
+@cindex @code{next}
+The interactive mode of @code{mixvm} lets you step by step execution of
+programs as well as breakpoint setting. Use @code{next} to step through
+the program, running its instructions one by one. To run our
+two-instruction @file{hello.mix} sample you can do the following:
+
+@example
+MIX > load hello
+Program loaded. Start address: 3000
+MIX > pc
+Current address: 3000
+MIX > next
+MIXAL HELLO WORLD
+Elapsed time: 1 /Total program time: 1 (Total uptime: 1)
+MIX > pc
+Current address: 3001
+MIX > next
+End of program reached at address 3002
+Elapsed time: 10 /Total program time: 11 (Total uptime: 11)
+MIX > pc
+Current address: 3002
+MIX > next
+MIXAL HELLO WORLD
+Elapsed time: 1 /Total program time: 1 (Total uptime: 12)
+MIX >
+MIX > run
+Running ...
+... done
+Elapsed time: 10 /Total program time: 11 (Total uptime: 22)
+MIX >
+@end example
+@noindent
+(As an aside, the above sample also shows how the virtual machine
+handles cummulative time statistics and automatic program restart).
+
+@cindex @code{sbpa}
+@cindex breakpoints
+
+You can set a breakpoint at a given address using the command
+@code{sbpa} (set breakpoint at address). When a breakpoint is set,
+@code{run} will stop before executing the instruction at the given
+address. Typing @code{run} again will resume program execution. Coming
+back to our hello world example, we would have:
+
+@example
+MIX > sbpa 3001
+Breakpoint set at address 3001
+MIX > run
+Running ...
+MIXAL HELLO WORLD
+... stopped: breakpoint at line 8 (address 3001)
+Elapsed time: 1 /Total program time: 1 (Total uptime: 23)
+MIX > run
+Running ...
+... done
+Elapsed time: 10 /Total program time: 11 (Total uptime: 33)
+MIX >
+@end example
+
+@cindex @code{sbp}
+@cindex breakpoints
+@noindent
+Note that, since we compiled @file{hello.mixal} with debug info
+enabled, the virtual machine is able to tell us the line in the
+source file corresponding to the breakpoint we are setting. As a
+matter of fact, you can directly set breakpoints at source code lines
+using the command @code{sbp LINE_NO}, e.g.
+
+@example
+MIX > sbp 4
+Breakpoint set at line 7
+MIX >
+@end example
+
+@noindent
+@code{sbp} sets the breakpoint at the first meaningful source code line;
+thus, in the above example we have requested a breakpoint at a line
+which does not correspond to a MIX instruction and the breakpoint is set
+at the first line containing a real instruction after the given one. To
+unset breakpoints, use @code{cbpa ADDRESS} and @code{cbp LINE_NO}, or
+@code{cabp} to remove all currently set breakpoints. You can also set
+conditional breakpoints, i.e., tell @code{mixvm} to interrupt program
+execution whenever a register, a memory cell, the comparison flag or the
+overflow toggle change using the commands @w{@code{sbp[rmco]}}
+(@pxref{Debug commands}).
+
+@cindex @code{psym}
+MIXAL lets you define symbolic constants, either using the @code{EQU}
+pseudoinstruction or starting an instruction line with a label (which
+assigns to the label the value of the current memory address). Each
+MIXAL program has, therefore, an associated symbol table which you can
+inspect using the @code{psym} command. For our hello world sample, you
+will obtain the following output:
+
+@example
+MIX > psym
+START:  3000
+TERM:  19
+MSG:  3002
+MIX >
+@end example
+
+Other useful commands for debugging are @code{strace} (which turns on
+tracing of executed intructions), @code{pbt} (which prints a backtrace
+of executed instructions) and @code{weval} (which evaluates
+w-expressions on the fly). For a complete description of all available
+MIX commands, @xref{mixvm}.
+
+@node Using mixguile, Using Scheme in mixvm and gmixvm, Running the program, Getting started
+@section Using @code{mixguile}
+
+With @code{mixguile} you can run a MIX simulator embedded in a Guile
+shell, that is, using Scheme functions and programs. As with
+@code{mixvm}, @code{mixguile} can be run both in interactive and
+non-interactive modes. The following subsections provide a quick tour on
+using this MIX emulator.
+
+@menu
+* The mixguile shell::          Using the Scheme MIX virtual machine.
+* Additional functions::        Scheme functions accessing the VM.
+* Defining new functions::      Defining your own Scheme functions.
+* Hook functions::              Using command and break hook functions.
+* Scheme scripts::
+@end menu
+
+@node The mixguile shell, Additional functions, Using mixguile, Using mixguile
+@subsection The @code{mixguile} shell
+@cindex Scheme
+@cindex @code{mixguile}
+@cindex REPL
+
+If you simply type
+
+@example
+mixguile @key{RET}
+@end example
+@noindent
+at the command prompt, you'll be presented a Guile shell prompt like
+this
+
+@example
+guile>
+@end example
+@noindent
+At this point, you have entered a Scheme read-eval-print loop (REPL)
+which offers you all the Guile functionality plus a new set of built-in
+procedures to execute and debug MIX programs. Each of the @code{mixvm}
+commands described in the previous sections (and in @pxref{mixvm}) have
+a Scheme function counterpart named after it by prepending the prefix
+@code{mix-} to its name. Thus, to load our hello world program, you can
+simply enter
+
+@example
+guile> (mix-load "hello")
+Program loaded. Start address: 3000
+guile>
+@end example
+@noindent
+and run it using @code{mix-run}:
+
+@example
+guile> (mix-run)
+Running ...
+MIXAL HELLO WORLD
+... done
+Elapsed time: 11 /Total program time: 11 (Total uptime: 11)
+guile>
+@end example
+@noindent
+In the same way, you can execute it step by step using the Scheme
+function @code{mix-next} or set a breakpoint:
+
+@example
+guile> (mix-sbp 4)
+Breakpoint set at line 5
+guile>
+@end example
+@noindent
+or, if you one to peek at a register contents:
+
+@example
+guile> (mix-preg 'A)
+rA: + 00 00 00 00 00 (0000000000)
+guile>
+@end example
+
+You get the idea: you have at your disposal all the @code{mixvm} and
+@code{gmixvm} commands by means of @code{mix-} functions. But, in case
+you are wondering, this is only the beginning. You also have at your
+disposal a whole Scheme interpreter, and you can, for instance, define
+new functions combining the @code{mix-} and all other Scheme
+primitives. In the next sections, you'll find examples of how to take
+advantage of the Guile interpreter.
+
+@node Additional functions, Defining new functions, The mixguile shell, Using mixguile
+@subsection Additional MIX Scheme functions
+
+The @code{mix-} function counterparts of the @code{mixvm} commands don't
+return any value, and are evaluated only for their side-effects
+(possibly including informational messages to the standard output and/or
+error stream). When writting your own Scheme functions to manipulate the
+MIX virtual machine within @code{mixguile} (@pxref{Defining new
+functions}), you'll probably need Scheme functions returning the value
+of the registers, memory cells and so on. Don't worry: @code{mixguile}
+also offers you such functions. For instance, to access the (numerical)
+value of a register you can use @code{mix-reg}:
+
+@example
+guile> (mix-reg 'I2)
+0
+guile>
+@end example
+@noindent
+Note that, unlike @code{(mix-preg 'I2)}, the expression @code{(mix-reg
+'I2)} in the above example evaluates to a Scheme number and does not
+produce any side-effect:
+
+@example
+guile> (number? (mix-reg 'I2))
+#t
+guile> (number? (mix-preg 'I2))
+rI2: + 00 00 (0000)
+#f
+guile>
+@end example
+
+In a similar fashion, you can access the memory contents using
+@code{(mix-cell)}, or the program counter using @code{(mix-loc)}:
+
+@example
+guile> (mix-cell 3000)
+786957541
+guile> (mix-loc)
+3002
+guile>
+@end example
+
+Other functions returning the contents of the virtual machine components
+are @code{mix-cmp} and @code{mix-over}, which eval to the value of the
+comparison flag and the overflow toggle respectively. For a complete
+list of these additional functions, @xref{mixguile}.
+
+In the next section, we'll see a sample of using these functions to
+extend @code{mixguile}'s functionality.
+
+@node Defining new functions, Hook functions, Additional functions, Using mixguile
+@subsection Defining new functions
+@cindex Scheme functions
+
+Scheme is a powerful language, and you can use it inside @code{mixguile}
+to easily extend the MIX interpreter's capabilities.  For example, you
+can easily define a function that loads a file, prints its name,
+executes it and, finally, shows the registers contents, all in one shot:
+
+@example
+guile> (define my-load-and-run  @key{RET}
+         (lambda (file)   @key{RET}
+           (mix-load file)   @key{RET}
+           (display "File loaded: ")   @key{RET}
+           (mix-pprog)   @key{RET}
+           (mix-run)   @key{RET}
+           (mix-preg)))   @key{RET}
+guile>
+@end example
+@noindent
+and use it to run your programs:
+
+@example
+guile> (my-load-and-run "hello")
+Program loaded. Start address: 3000
+File loaded: hello.mix
+Running ...
+MIXAL HELLO WORLD
+... done
+Elapsed time: 11 /Total program time: 11 (Total uptime: 33)
+rA: + 00 00 00 00 00 (0000000000)
+rX: + 00 00 00 00 00 (0000000000)
+rJ: + 00 00 (0000)
+rI1: + 00 00 (0000)	rI2: + 00 00 (0000)
+rI3: + 00 00 (0000)	rI4: + 00 00 (0000)
+rI5: + 00 00 (0000)	rI6: + 00 00 (0000)
+guile>
+@end example
+
+
+Or, maybe, you want a function which sets a breakpoint at a specified
+line number before executing it:
+
+@example
+guile> (define my-load-and-run-with-bp
+         (lambda (file line)
+           (mix-load file)
+           (mix-sbp line)
+           (mix-run)))
+guile> (my-load-and-run-with-bp "samples/primes" 10)
+Program loaded. Start address: 3000
+Breakpoint set at line 10
+Running ...
+... stopped: breakpoint at line 10 (address 3001)
+Elapsed time: 1 /Total program time: 1 (Total uptime: 45)
+guile>
+@end example
+
+As a third example, the following function loads a program, runs it and
+prints the contents of the memory between the program's start and end
+addresses:
+
+@example
+guile> (define my-run
+         (lambda (file)
+           (mix-load file)
+           (let ((start (mix-loc)))
+             (mix-run)
+             (mix-pmem start (mix-loc)))))
+guile> (my-run "hello")
+Program loaded. Start address: 3000
+Running ...
+MIXAL HELLO WORLD
+... done
+Elapsed time: 11 /Total program time: 11 (Total uptime: 11)
+3000: + 46 58 00 19 37 (0786957541)
+3001: + 00 00 00 02 05 (0000000133)
+3002: + 14 09 27 01 13 (0237350989)
+guile>
+@end example
+
+
+As you can see, the possibilities are virtually unlimited. Of course,
+you don't need to type a function definition each time you start
+@code{mixguile}. You can write it in a file, and load it using Scheme's
+@code{load} function. For instance, you can create a file named, say,
+@file{functions.scm} with your definitions (or any Scheme expression)
+and load it at the @code{mixguile} prompt:
+
+@example
+guile> (load "functions.scm")
+@end example
+
+Alternatively, you can make @code{mixguile} to load it for you. When
+@code{mixguile} starts, it looks for a file named @file{mixguile.scm} in
+your MDK configuration directory (@file{~/.mdk}) and, if it exists,
+loads it before entering the REPL. Therefore, you can copy your
+definitions in that file, or load the @file{functions.scm} file in
+@file{mixguile.scm}.
+
+@node Hook functions, Scheme scripts, Defining new functions, Using mixguile
+@subsection Hook functions
+@cindex hook function
+@cindex pre-hook
+@cindex post-hook
+
+Hooks are functions called before or after a given event occurs. In
+@code{mixguile}, you can define command and break hooks, which are
+associated, respectively, with command execution and program
+interruption events. The following sections give you a tutorial on using
+hook functions within @code{mixguile}.
+
+@menu
+* Command hooks::
+* Break hooks::
+@end menu
+
+@node Command hooks, Break hooks, Hook functions, Hook functions
+@subsubsection Command hooks
+
+In the previous section, we have seen how to extend @code{mixguile}'s
+functionality through the use of user defined functions. Frequently,
+you'll write new functions that improve in some way the workings of a
+built-in @code{mixvm} command, following this pattern:
+
+@enumerate a
+@item
+Prepare the command execution
+@item
+Execute the desired command
+@item
+Perform post execution operations
+@end enumerate
+
+We call the functions executed in step (a) @dfn{pre-hook}s, and those of
+step @dfn{post-hook}s of the given command. @code{mixguile} lets you
+specify pre- and post-hooks for any @code{mixvm} command using the
+@code{mix-add-pre-hook} and  @code{mix-add-post-hook} functions, which
+take as arguments a symbol naming the command and a function to be
+executed before (resp. after) the command. In other words,
+@code{mixguile} will execute for you steps (a) and (c) above whenever
+you eval (b). The hook functions must take a single argument, which is a
+string list of the command's arguments. As an example, let us define the
+following hooks for the @code{next} command:
+
+@example
+(define next-pre-hook
+  (lambda (arglist)
+    (mix-slog #f)))
+
+(define next-post-hook
+  (lambda (arglist)
+    (display "Stopped at line ")
+    (display (mix-src-line-no))
+    (display ": ")
+    (display (mix-src-line))
+    (newline)
+    (mix-slog #t)))
+@end example
+@noindent
+In these functions, we are using the function @code{mix-slog} to turn
+off the informational messages produced by the virtual machine, since we
+are providing our own ones in the post hook function. To install these
+hooks, we would write:
+
+@example
+(mix-add-pre-hook 'next next-pre-hook)
+(mix-add-post-hook 'next next-post-hook)
+@end example
+@noindent
+Assuming we have put the above expressions in @code{mixguile}'s
+initialisation file, we would obtain the following results when
+evaluating @code{mix-next}:
+
+@example
+guile> (mix-next)
+MIXAL HELLO WORLD
+Stopped at line 6:             HLT
+guile>
+@end example
+
+As a second, more elaborated, example, let's define hooks which print
+the address and contents of a cell being modified using @code{smem}. The
+hook functions could be something like this:
+
+@example
+(define smem-pre-hook
+  (lambda (arglist)
+    (if (eq? (length arglist) 2)
+        (begin
+          (display "Changing address ")
+          (display (car arglist))
+          (newline)
+          (display "Old contents: ")
+          (display (mix-cell (string->number (car arglist))))
+          (newline))
+        (error "Wrong arguments" arglist))))
+
+(define smem-post-hook
+  (lambda (arglist)
+    (if (eq? (length arglist) 2)
+        (begin
+          (display "New contents: ")
+          (display (mix-cell (string->number (car arglist))))
+          (newline)))))
+@end example
+@noindent
+and we can install them using
+
+@example
+(mix-add-pre-hook 'smem smem-pre-hook)
+(mix-add-post-hook 'smem smem-post-hook)
+@end example
+@noindent
+Aferwards, a sample execution of @code{mix-smem} would look like this:
+
+@example
+guile> (mix-smem 2000 100)
+Changing address 2000
+Old contents: 0
+New contents: 100
+guile>
+@end example
+
+@cindex global hook
+
+You can add any number of hooks to a given command. They will be
+executed in the same order as they are registered. You can also define
+global post (pre) hooks, which will be called before (after) any
+@code{mixvm} command is executed. Global hook functions must admit two
+arguments, namely, a string naming the invoked command and a string list
+of its arguments, and they are installed using the Scheme functions
+@code{mix-add-global-pre-hook} and @code{mix-add-global-post-hook}. A
+simple example of global hook would be:
+
+@example
+guile> (define pre-hook
+         (lambda (cmd args)
+           (display cmd)
+           (display " invoked with arguments ")
+           (display args)
+           (newline)))
+guile> (mix-add-global-pre-hook pre-hook)
+ok
+guile> (mix-pmem 120 125)
+pmem invoked with arguments (120-125)
+0120: + 00 00 00 00 00 (0000000000)
+0121: + 00 00 00 00 00 (0000000000)
+0122: + 00 00 00 00 00 (0000000000)
+0123: + 00 00 00 00 00 (0000000000)
+0124: + 00 00 00 00 00 (0000000000)
+0125: + 00 00 00 00 00 (0000000000)
+guile>
+@end example
+
+Note that if you invoke @code{mixvm} commands within a global hook, its
+associated command hooks will be run. Thus, if you have installed both
+the @code{next} hooks described earlier and the global hook above,
+executing @code{mix-next} will yield the following result:
+
+@example
+guile> (mix-next 5)
+next invoked with arguments (5)
+slog invoked with arguments (off)
+MIXAL HELLO WORLD
+Stopped at line 7: MSG         ALF   "MIXAL"
+slog invoked with arguments (on)
+guile>
+@end example
+
+Adventurous readers may see the above global hook as the beginning of a
+command log utility or a macro recorder that saves your commands for
+replay.
+
+@node Break hooks,  , Command hooks, Hook functions
+@subsubsection Break hooks
+
+@cindex break hook
+
+We have seen in the previous section how to associate hooks to command
+execution, but they are not the whole story. You can also associate hook
+functions to program interruption, that is, specify functions that
+should be called every time the execution of a MIX program is stopped
+due to the presence of a breakpoint, either explicit or
+conditional. Break hooks take as arguments the line number and memory
+address at which the break occurred. A simple hook that logs the line
+and address of the breakpoint could be defined as:
+
+@example
+(define break-hook
+  (lambda (line address)
+    (display "Breakpoint encountered at line ")
+    (display line)
+    (display " and address ")
+    (display address)
+    (newline)))
+@end example
+@noindent
+and installed for explicit and conditional breakpoints using
+
+@example
+(mix-add-break-hook break-hook)
+(mix-add-cond-break-hook break-hook)
+@end example
+@noindent
+after that, every time the virtual machine encounters a breakpoint,
+@code{break-code} shall be evaluated for you@footnote{You may have
+noticed that break hooks can be implemented in terms of command hooks
+associated to @code{mix-run} and @code{mix-next}. As a matter of fact,
+they @emph{are} implemented this way: take a look at the file
+@file{@emph{install_dir}/share/mdk/mix-vm-stat.scm} if you are curious.}.
+
+@node Scheme scripts,  , Hook functions, Using mixguile
+@subsection Scheme scripts
+@cindex Scheme script
+@cindex non-interactive
+
+Another useful way of using @code{mixguile} is writing executable
+scripts that perform a set of commands for you. This is done using the
+@code{mixguile} switch @code{-s} (being a Guile shell, @code{mixguile}
+accepts all the command options of @code{guile}; type @code{mixguile -h}
+for a list of all available command options). For instance, if you have
+a very useful MIX program @file{foo.mix} which you want to run often,
+you don't have to fire a MIX virtual machine, load and run it every
+time; you can write a Scheme script instead:
+
+@example
+#! /usr/bin/mixguile -s
+!#
+;;; runprimes: execute the primes.mix program
+
+;; load the file you want to run
+(mix-load "../samples/primes")
+;; execute it
+(mix-run)
+;; print the contents of registers
+(mix-pall)
+;; ...
+@end example
+
+Just save the above script to a file named, say, @file{runtest}, make it
+executable (@code{chmod +x runtest}), and, well, execute it from the
+Unix shell:
+
+@example
+$ ./runtest
+Program loaded. Start address: 3000
+Running ...
+... done
+Elapsed time: 190908 /Total program time: 190908 (Total uptime: 190908)
+rA: + 30 30 30 30 30 (0511305630)
+rX: + 30 30 32 32 39 (0511313959)
+rJ: + 47 18 (3026)
+rI1: + 00 00 (0000)     rI2: + 55 51 (3571)
+rI3: + 00 19 (0019)     rI4: + 31 51 (2035)
+rI5: + 00 00 (0000)     rI6: + 00 00 (0000)
+Overflow: F
+Cmp: L
+$
+@end example
+
+Note that this is far more flexible that running programs
+non-interactively using @code{mixvm} (@pxref{Non-interactive mode}), for
+you can execute any combination of commands you want from a Scheme
+script (not just running and dumping the registers). For additional
+@code{mixguile} command line options, see @ref{Invoking mixguile}.
+
+@node Using Scheme in mixvm and gmixvm,  , Using mixguile, Getting started
+@section  Using Scheme in @code{mixvm} and @code{gmixvm}
+@cindex @code{scmf}
+
+In the previous section (@pxref{Using mixguile}) we have seen how the
+Guile shell @code{mixguile} offers you the possibility of using Scheme
+to manipulate a MIx virtual machine and extend the set of commands
+offered by @code{mixvm} and @code{gmixvm}. This possibility is not
+limited to the @code{mixguile} shell. Actually, both @code{mixvm} and
+@code{gmixvm} incorporate an embedded Guile interpreter, and can
+evaluate Scheme expressions. To evaluate a single-line expression at the
+@code{mixvm} or @code{gmixvm} command prompt, simply write it and press
+return (the command parser will recognise it as a Scheme expression
+because it is parenthesized, and will pass it to the Guile
+interpreter). A sample @code{mixvm} session using Scheme expressions
+could be:
+
+@example
+MIX > load hello
+Program loaded. Start address: 3000
+MIX > (define a (mix-loc))
+MIX > run
+Running ...
+MIXAL HELLO WORLD
+... done
+Elapsed time: 11 /Total program time: 11 (Total uptime: 11)
+MIX > (mix-pmem a)
+3000: + 46 58 00 19 37 (0786957541)
+MIX > (mix-pmem (mix-loc))
+3002: + 14 09 27 01 13 (0237350989)
+MIX >
+@end example
+
+You can also load and evaluate a file, using the @code{scmf}
+command like this:
+
+@example
+MIX> scmf /path/to/file/file.scm
+@end example
+
+Therefore, you have at your disposal all the @code{mixguile} goodies
+described above (new functions, new command definitions, hooks...)
+inside @code{mixvm} and @code{gmixvm}. In other words, these programs
+are extensible using Scheme. See @ref{Using mixguile} for examples of
+how to do it.
+
diff --git a/doc/mdk_index.texi b/doc/mdk_index.texi
new file mode 100644
index 0000000..68f3c48
--- /dev/null
+++ b/doc/mdk_index.texi
@@ -0,0 +1,14 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_index.texi,v 1.7 2004/08/03 13:23:06 jao Exp $
+
+@node Concept Index, Instructions and commands, Copying, Top
+@unnumbered Concept Index
+
+@cindex tail recursion
+@printindex cp
+
diff --git a/doc/mdk_install.texi b/doc/mdk_install.texi
new file mode 100644
index 0000000..08a44e2
--- /dev/null
+++ b/doc/mdk_install.texi
@@ -0,0 +1,287 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2002, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@node Installing MDK, MIX and MIXAL tutorial, Acknowledgments, Top
+@comment  node-name,  next,  previous,  up
+@chapter Installing @sc{mdk}
+
+@menu
+* Download::
+* Requirements::
+* Basic installation::
+* Emacs support::
+* Special configure flags::
+* Supported platforms::
+@end menu
+
+@node Download, Requirements, Installing MDK, Installing MDK
+@comment  node-name,  next,  previous,  up
+@section Download the source tarball
+
+GNU @sc{mdk} is distributed as a source tarball available for download in
+the following @acronym{URL}s:
+
+@itemize @bullet
+@item
+@url{ftp://ftp.gnu.org/pub/gnu/mdk}
+@item
+@uref{http://www.gnu.org/prep/ftp.html, GNU mirrors}
+@item
+@uref{http://sourceforge.net/project/showfiles.php?group_id=13897}
+@end itemize
+
+The above sites contain the latest stable releases of @sc{mdk}. The
+development branch is available at:
+
+@itemize @bullet
+@item
+@uref{https://savannah.gnu.org/cvs/?group_id=118}
+@end itemize
+
+After you have downloaded the source tarball, unpack it in a directory
+of your choice using the command:
+
+@example
+tar xfvz mdk-X.Y.tar.gz
+@end example
+
+@noindent
+where @var{X.Y} stands for the downloaded version (the current stable
+release being version @value{VERSION}).
+
+@node Requirements, Basic installation, Download, Installing MDK
+@comment  node-name,  next,  previous,  up
+@section Requirements
+
+In order to build and install @sc{mdk}, you will need the following
+libraries installed in your system:
+
+@itemize @minus
+@item
+@uref{http://www.gtk.org, GLIB 2.4.0} (required)
+@item
+@uref{http://www.gnu.org/software/flex/flex.html, GNU Flex 2.5} (required)
+@item
+@uref{http://www.gtk.org, GTK 2.4.0} (optional)
+@item
+@uref{http://ftp.gnome.org/pub/GNOME/sources/libglade/2.4/, Libglade
+2.4.0}
+(optional)
+@item
+@uref{http://cnswww.cns.cwru.edu/php/chet/readline/rltop.html, GNU
+Readline}
+(optional)
+@item
+@uref{http://www.gnu.org/software/guile, GNU Libguile 1.6} (optional)
+@end itemize
+
+If present, readline and history are used to provide command completion
+and history management to the command line MIX virtual machine, @code{mixvm}.
+GTK+ and libglade are needed if you want to build the graphical
+interface to the MIX virtual machine, @code{gmixvm}. Finally, if
+libguile is found, the @sc{mdk} utilities will be compiled with Guile
+support and will be extensible using Scheme.
+
+@strong{Please note}: you need both the libraries @emph{and} the
+headers; this means both the library package and the @file{-dev} package
+if you do not compile your libraries yourself (ex: installing
+@file{libgtk2.0-0} and @file{libgtk2.0-0-dev} on Debian).
+
+@node Basic installation, Emacs support, Requirements, Installing MDK
+@comment  node-name,  next,  previous,  up
+@section Basic installation
+
+@sc{mdk} uses GNU Autoconf and Automake tools, and, therefore, should
+be built and installed without hassle using the following commands
+inside the source directory:
+
+@example
+./configure
+make
+make install
+@end example
+
+@noindent
+where the last one must be run as root.
+
+The first command, @code{configure}, will setup the makefiles for your
+system. In particular, @code{configure} will look for GTK+ and libglade,
+and, if they are present, will generate the appropiate makefiles for
+building the @code{gmixvm} graphical user interface. Upon completion,
+you should see a message with the configuration results like the
+following:
+
+@example
+*** GNU MDK 1.2 has been successfully configured. ***
+
+Type 'make' to build the following utilities:
+    - mixasm (MIX assembler)
+    - mixvm (MIX virtual machine, with readline support,
+             with guile support)
+    - gmixvm (mixvm GTK+ GUI, with guile support)
+    - mixguile (the mixvm guile shell)
+@end example
+
+@noindent
+where the last lines may be missing if you lack the above mentioned
+libraries.
+
+The next command, @code{make}, will actually build the @sc{mdk} programs
+in the following locations:
+
+@itemize @minus
+@item
+@file{mixutils/mixasm}
+@item
+@file{mixutils/mixvm}
+@item
+@file{mixgtk/gmixvm}
+@item
+@file{mixguile/mixguile}
+@end itemize
+
+You can run these programs from within their directories, but I
+recommend you to install them in proper locations using @code{make
+install} from a root shell.
+
+@node Emacs support, Special configure flags, Basic installation, Installing MDK
+@comment  node-name,  next,  previous,  up
+@section Emacs support
+
+@sc{mdk} includes extensive support for Emacs. Upon installation, all
+the elisp code is installed in @file{PREFIX/share/mdk}, where
+@file{PREFIX} stands for your installation root directory (e.g.
+@file{/usr/local}). You can copy the elisp files to a directory that
+is in your load-path, or you can add the above directory to it.
+Assuming that the installing prefix is @file{/usr/local},
+you can do it by adding to your @file{.emacs} file the following line:
+
+@lisp
+(setq load-path (cons "/usr/local/share/mdk" load-path))
+@end lisp
+
+@code{MIXAL} programs can be written using Emacs and the elisp program
+@file{share/mdk/mixal-mode.el}, contributed by @value{PIETER}. It
+provides font locking, interactive help, compiling assistance and
+invocation of the @code{MIX} virtual machine via a new major mode
+called @code{mixal-mode}. To start @code{mixal-mode} automatically
+whenever you edit a @code{MIXAL} source file, add the following lines
+to your @file{.emacs} file:
+
+@lisp
+(autoload 'mixal-mode "mixal-mode" t)
+(add-to-list 'auto-mode-alist '("\\.mixal\\'" . mixal-mode))
+@end lisp
+
+In addition, @code{mixvm} can be run within an Emacs @acronym{GUD}
+buffer using the elisp program @file{share/mdk/mixvm.el}, contributed
+by @value{PHILIP}. @file{mixvm.el} provides an interface between
+@sc{mdk}'s @code{mixvm} and Emacs, via @acronym{GUD}. Place this file
+in your load-path, optionally adding the following line to your
+@file{.emacs} file:
+
+@lisp
+(autoload 'mixvm "mixvm" "mixvm/gud interaction" t)
+@end lisp
+
+
+@node Special configure flags, Supported platforms, Emacs support, Installing MDK
+@comment  node-name,  next,  previous,  up
+@section Special configure flags
+
+You can fine-tune the configuration process using the following
+switches with configure:
+
+@defopt @w{--enable-gui[=yes|no]}
+@defoptx --disable-gui
+Enables/disables the build of the MIX virtual machine GUI
+(@code{gmixvm}). If the required libraries are missing
+(@pxref{Requirements}) the configure script with automatically disable
+this feature.
+@end defopt
+
+@defopt @w{--with-guile[=yes|no]}
+@defoptx --without-guile
+Enables/disables the Guile support for @code{mixvm} and @code{gmixvm},
+and the build of @code{mixguile}.  If the
+required libraries are missing (@pxref{Requirements}) the configure
+script with automatically disable this feature.
+@end defopt
+
+@defopt @w{--with-readline[=yes|no]}
+@defoptx --without-readline
+Enables/disables the GNU Readline support for @code{mixvm}.  If the
+required libraries are missing (@pxref{Requirements}) the configure
+script with automatically disable this feature.
+@end defopt
+
+For additional, boilerplate configure options, see the @file{INSTALL}
+file, or run
+
+@example
+configure --help
+@end example
+
+@node Supported platforms,  , Special configure flags, Installing MDK
+@comment  node-name,  next,  previous,  up
+@section Supported platforms
+
+GNU MDK has been tested in the following platforms:
+
+@itemize
+@item
+Debian GNU/Linux 2.2, 2.3, 3.0, 3.1, 3.2
+@item
+Redhat GNU/Linux 8.0 (Ronald Cole), 7.0 (Agustin Navarro), 6.2
+(Roberto Ferrero)
+@item
+Mandrake 8.0 (Agustin Navarro)
+@item
+FreeBSD 4.2, 4.3, 4.4, 4.5 (Ying-Chieh Liao), 5.2
+@item
+Solaris 2.8/gcc 2.95.3 (Stephen Ramsay)
+@item
+MS Windows 98 SE/Cygwin 1.1.8-2 (Christoph von
+Nathusius)@footnote{Caveats: Christoph has only tested @code{mixvm} and
+@code{mixasm} on this platform, using @code{gcc} 2.95.3-2, @code{GLIB}
+1.2.10 and @code{GNUreadline} 4.1-2. He has reported missing history
+functionalities on a first try. If you find problems with
+history/readline functionality, please try a newer/manually installed
+readline version.}
+@item
+Mac OS X 10.1.2 (Johan Swanljung)
+@item
+AMD Athlon, GNU/Linux version 2.4.2-2smp (Red Hat 7.1 (Seawolf)) (N.
+H. F. Beebe)
+@item
+Apple PowerPC G3, GNU/Linux 2.2.18-4hpmac (Red Hat Linux/PPC
+2000 Q4) (N. H. F. Beebe)
+@item
+DEC Alpha, GNU/Linux 2.2.19-6.2.1 (Red Hat 6.2) (N. H. F. Beebe)
+@item
+Compaq/DEC Alpha OSF/1 4.0F [ONLY after adding rsync's snprintf()
+implementation] (N. H. F. Beebe)
+@item
+IBM PowerPC AIX 4.2 (N. H. F. Beebe)
+@item
+Intel Pentium III, GNU/Linux 2.4.9-31smp (Red Hat 7.2 (Enigma)) (N. H.
+F. Beebe)
+@item
+SGI Origin 200, IRIX 6.5 (N.
+H. F. Beebe)
+@item
+Sun SPARC, GNU/Linux 2.2.19-6.2.1 (Red Hat 6.2) (N. H. F. Beebe)
+@item
+Sun SPARC, Solaris 2.8 (N. H. F. Beebe)
+@end itemize
+
+@sc{mdk} will probably work on any GNU/Linux or BSD platform. If you
+try it in a platform not listed above, please send a mail to
+@email{jao@@gnu.org, the author}.
+
+
+
+
diff --git a/doc/mdk_intro.texi b/doc/mdk_intro.texi
new file mode 100644
index 0000000..b4ce2ad
--- /dev/null
+++ b/doc/mdk_intro.texi
@@ -0,0 +1,70 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_intro.texi,v 1.8 2004/08/03 13:23:06 jao Exp $
+
+@node Introduction, Acknowledgments, Top, Top
+@comment  node-name,  next,  previous,  up
+@unnumbered Introduction
+@cindex Introduction
+
+In his book series @cite{The Art of Computer Programming} (published by
+Addison Wesley), D. Knuth uses an imaginary computer, the MIX, and its
+associated machine-code and assembly languages to ilustrate the
+concepts and algorithms as they are presented.
+
+The MIX's architecture is a simplified version of those found in real
+CISC CPUs, and the MIX assembly language (MIXAL) provides a set of
+primitives that will be very familiar to any person with a minimum
+experience in assembly programming. The MIX/MIXAL definition is powerful
+and complete enough to provide a virtual development platform for
+writing quite complex programs, and close enough to real computers to be
+worth using when learning programming techniques. At any rate, if you
+want to learn or improve your programming skills, a MIX development
+environment would come in handy.
+
+The @sc{mdk} package aims at providing such virtual development
+environment on a GNU box. Thus, @sc{mdk} offers you a set of utilities
+to simulate the MIX computer and to write, compile, run and debug MIXAL
+programs. As of version @value{VERSION}, @sc{mdk} includes
+the following programs:
+
+@table @code
+@item mixasm
+MIXAL assembler. Assembler which translates MIXAL source files into
+programs that can be run (and debugged) by @code{mixvm}, @code{mixguile}
+or @code{gmixvm}.
+@item mixvm
+MIX virtual machine. Emulation of the MIX computer with a @acronym{CLI}.
+@item gmixvm
+A GTK+ GUI for the MIX virtual machine. Provides all of @code{mixvm}
+functionality accessible through a graphical interface.
+@item mixguile
+A Guile shell, with an embedded MIX virtual machine and built-in
+commands to manipulate it using Scheme.
+@item mixal-mode.el
+An Emacs major mode for MIXAL source files editing, providing syntax
+highlighting, documentation lookup and invocation of @code{mixvm}
+within Emacs.
+@item mixvm.el
+This elisp program allows running @code{mixvm} inside an Emacs GUD
+buffer, providing concurrent edition and debugging of MIXAL programs.
+@end table
+
+@code{mixvm} and @code{gmixvm} implement a simulator of the MIX
+computer, giving you a virtual machine for executing and debugging MIX
+programs. These binary programs could be written by hand, but it is
+easier to produce them compiling MIXAL source files, using the MIXAL
+assembler @code{mixasm}. On the other hand, @code{mixguile} offers you
+the possibility of manipulating a MIX virtual machine through a set of
+Scheme functions, so that you can use this programming language to
+interact with the virtual machine. In addition, @code{mixvm} and
+@code{gmixvm} are also able to interpret Scheme scripts (using an
+embedded Guile interpreter), that is, you can use Scheme as an extension
+language to add new functionalities to these programs.
+
+This manual gives you a tutorial of MIX and MIXAL, and a thorough
+description of the use of the @sc{mdk} utilities.
diff --git a/doc/mdk_mixasm.texi b/doc/mdk_mixasm.texi
new file mode 100644
index 0000000..fa144a7
--- /dev/null
+++ b/doc/mdk_mixasm.texi
@@ -0,0 +1,89 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_mixasm.texi,v 1.10 2004/08/05 21:32:46 jao Exp $
+
+@node mixasm, mixvm, Emacs tools, Top
+@comment  node-name,  next,  previous,  up
+@chapter @code{mixasm}, the MIXAL assembler
+@cindex @code{mixasm}
+@cindex MIXAL
+@cindex assembler
+
+MIX programs, as executed by @code{mixvm}, are composed of binary
+instructions loaded into the virtual machine memory as MIX
+words. Although you could write your MIX programs directly as a series
+of words in binary format, you have at your disposal a more friendly
+assembly language, MIXAL (@pxref{MIXAL}) which is compiled into binary
+form by @code{mixasm}, the MIXAL assembler included in @sc{mdk}. In this
+chapter, you will find a complete description of @code{mixasm} options.
+
+@menu
+* Invoking mixasm::
+@end menu
+
+@node Invoking mixasm,  , mixasm, mixasm
+@comment  node-name,  next,  previous,  up
+@section Invoking @code{mixasm}
+
+In its simplest form, @code{mixasm} is invoked with a single argument,
+which is the name of the MIXAL file to be compiled, e.g.
+
+@example
+mixasm hello
+@end example
+
+@noindent
+will compile either @file{hello} or @file{hello.mixal}, producing a
+binary file named @file{hello.mix} if no errors are found.
+
+In addition, @code{mixasm} can be invoked with the following command
+line options (note, that, following GNU's conventions, we provide a long
+option name for each available single letter switch):
+
+@example
+mixasm [-vhulO] [-o OUTPUT_FILE] [--version] [--help] [--usage]
+       [--ndebug] [--output=OUTPUT_FILE] [--list[=LIST_FILE]] file
+@end example
+
+@noindent
+The meaning of these options is as follows:
+
+@defopt -v
+@defoptx --version
+Prints version and copyleft information and exits.
+@end defopt
+
+@defopt -h
+@defoptx --help
+@defoptx -u
+@defoptx --usage
+Prints a summary of available options and exits.
+@end defopt
+
+@defopt -O
+@defoptx --ndebug
+Do not include debugging information in the compiled file, saving
+space but disallowing breakpoint setting at source level and symbol
+table inspection under @code{mixvm}.
+@end defopt
+
+@defopt -o output_file
+@defoptx --output=output_file
+By default, the given source file @var{file.mixal} is compiled into
+@var{file.mix}. You can provide a different name for the output file
+using this option.
+@end defopt
+
+@defopt -l
+@defoptx @w{--list[=list_file]}
+@cindex .mls file
+This option causes @code{mixasm} to produce, in addion to the
+@file{.mix} file, an ASCII file containing a summary of the compilation
+results. The file is named after the MIXAL source file, changing its
+extension to @file{.mls} if no argument is provided; otherwise, the
+listing file is named according to the argument.
+@end defopt
diff --git a/doc/mdk_mixguile.texi b/doc/mdk_mixguile.texi
new file mode 100644
index 0000000..2d6ac65
--- /dev/null
+++ b/doc/mdk_mixguile.texi
@@ -0,0 +1,445 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_mixguile.texi,v 1.5 2004/08/03 13:23:06 jao Exp $
+
+@node mixguile, Problems, gmixvm, Top
+@chapter @code{mixguile}, the Scheme virtual machine
+@cindex @code{mixguile}
+
+This chapter provides a reference to using @code{mixguile} and the
+Scheme function library giving access to the MIX virtual machine in the
+@sc{mdk} emulators (@code{mixguile}, @code{mixvm} and @code{gmixvm}). See
+@ref{Using mixguile} for a tutorial, step by step introduction to
+@code{mixguile} and using Scheme as an extension language for the
+@sc{mdk} MIX virtual machines.
+
+@menu
+* Invoking mixguile::           Command line options.
+* Scheme functions reference::  Scheme functions accessing the VM.
+@end menu
+
+@node Invoking mixguile, Scheme functions reference, mixguile, mixguile
+@section Invoking @code{mixguile}
+@cindex @code{mixguile} options
+
+Invoking @code{mixguile} without arguments will enter the Guile REPL
+(read-eval-print loop) after loading, if it exists, the user's
+initialisation file (@file{~/.mdk/mixguile.scm}).
+
+@code{mixguile} accepts the same command line options than Guile:
+
+@example
+mixguile [-s SCRIPT] [-c EXPR] [-l FILE] [-e FUNCTION] [-qhv]
+         [--help] [--version]
+@end example
+
+The meaning of these options is as follows:
+
+@defopt -h
+@defoptx --help
+Prints usage summary and exits.
+@end defopt
+
+@defopt -v
+@defoptx --version
+Prints version and copyleft information and exits.
+@end defopt
+
+@defopt -s SCRIPT
+Loads Scheme code from @var{script}, evaluates it and exits. This option
+can be used to write executable Scheme scripts, as described in
+@ref{Scheme scripts}.
+@end defopt
+
+@defopt -c EXPR
+Evaluates the given Scheme expression and exits.
+@end defopt
+
+@defopt -l FILE
+Loads the given Scheme file and enters the REPL (read-eval-print loop).
+@end defopt
+
+@defopt -e FUNCTION
+After reading the script, executes the given function using the provided
+command line arguments. For instance, you can write the following Scheme
+script:
+
+@example
+#! /usr/bin/mixguile \
+-e main -s
+!#
+
+;;; execute a given program and print the registers.
+
+(define main
+  (lambda (args)
+    ;; load the file provided as a command line argument
+    (mix-load (cadr args))
+    ;; execute it
+    (mix-run)
+    ;; print the contents of registers
+    (mix-pall)))
+
+@end example
+@noindent
+save it in a file called, say, @file{foo}, make it executable, and run
+it as
+
+@example
+$ ./foo hello
+@end example
+@noindent
+This invocation will cause the evaluation of the @code{main} function
+with a list of command line parameters as its argument (@code{("./foo"
+"hello")} in the above example. Note that command line options to
+mixguile must be written in their own line after the @code{\} symbol.
+@end defopt
+
+@defopt -q
+Do not load user's initialisation file. When @code{mixguile} starts up,
+it looks for a file named @file{mixguile.scm} in the user's @sc{mdk}
+configuration directory (@file{~/.mdk}), and loads it if it exists. This
+option tells @code{mixguile} to skip this initialisation file loading.
+@end defopt
+
+
+@node Scheme functions reference,  , Invoking mixguile, mixguile
+@section Scheme functions reference
+
+As we have previously pointed out, @code{mixguile} embeds a MIX virtual
+machine that can be accessed through a set of Scheme functions, that is,
+of a Scheme library. Conversely, @code{mixvm} and @code{gmixvm} contain
+a Guile interpreter, and are able to use this same Scheme library, as
+well as all the other Guile/Scheme primitives and any user defined
+function. Therefore, you have at your disposal a powerful programming
+language, Scheme, to extend the @sc{mdk} virtual machine emulators (see
+@ref{Using Scheme in mixvm and gmixvm} for samples of how to do it).
+
+The following subsections describe available functions the MIX/Scheme
+library.
+
+@menu
+* mixvm wrappers::              Functions invoking mixvm commands.
+* Hooks::                       Adding hooks to mixvm commands.
+* Additional VM functions::     Functions accessing the MIX virtual machine.
+@end menu
+
+@node mixvm wrappers, Hooks, Scheme functions reference, Scheme functions reference
+@subsection @code{mixvm} command wrappers
+
+For each of the @code{mixvm} commands listed in @ref{Commands}, there is
+a corresponding Scheme function named by prefixing the command name with
+@code{mix-} (e.g., @code{mix-load}, @code{mix-run} and so on). These
+command wrappers are implemented using a generic command dispatching
+function:
+
+@defun mixvm-cmd command argument
+Dispatchs the given @var{command} to the MIX virtual appending the
+provided @var{argument}. Both @var{command} and @code{argument} must be
+strings. The net result is as writing "@var{command} @var{argument}" at
+the @code{mixvm} or @code{gmixvm} command prompt.
+@end defun
+
+For instance, you can invoke the @code{run} command at the @code{mixvm}
+prompt in three equivalent ways:
+
+@example
+MIX > run hello
+MIX > (mix-run "hello")
+MIX > (mixvm-cmd "run" "hello")
+@end example
+@noindent
+(only the two last forms can be used at the @code{mixguile} prompt or
+inside a Scheme script).
+
+The @code{mix-} functions evaluate to a unspecified value. If you want
+to check the result of the last @code{mixvm} command invocation, use the
+@code{mix-last-result} function:
+
+@defun mix-last-result
+Returns @var{#t} if the last @code{mixvm} command invocation was
+successful, @var{#f} otherwise.
+@end defun
+@noindent
+Using this function, we could improve the script for running a program
+presented in the previous section by adding error checking:
+
+
+@example
+#! /usr/bin/mixguile \
+-e main -s
+!#
+
+;;; Execute a given program and print the registers.
+
+(define main
+  (lambda (args)
+    ;; load the file provided as a command line argument
+    (mix-load (cadr args))
+    ;; execute it if mix-load succeeded
+    (if (mix-last-result) (mix-run))
+    ;; print the contents of registers if the above commands succeded
+    (if (mix-last-result) (mix-pall))))
+@end example
+
+Please, refer to @ref{Commands} for a list of available commands. Given
+the description of a @code{mixvm}, it is straightforward to use its
+Scheme counterpart and, therefore, we shall not give a complete
+description of these functions here. Instead, we will only mention those
+wrappers that exhibit a treatment of their differing from that of their
+command counterpart.
+
+@defun mix-preg [register]
+@defunx mix-sreg register value
+The argument @var{register} of these functions can be either a string or
+a symbol representing the desired register. For instance, the following
+invocations are equivalent:
+
+@example
+(mix-preg 'I1)
+(mix-preg "I1")
+@end example
+@end defun
+
+@defun mix-pmem from [to]
+The command @code{pmem} takes a single argument which can be either a
+cell number or a range of the form @code{FROM-TO}. This function takes
+one argument to ask for a single memory cell contents, or two parameters
+to ask for a range. For instance, the following commands are equivalent:
+
+@example
+MIX > pmem 10-12
+0010: + 00 00 00 00 00 (0000000000)
+0011: + 00 00 00 00 00 (0000000000)
+0012: + 00 00 00 00 00 (0000000000)
+MIX > (mix-pmem 10 12)
+0010: + 00 00 00 00 00 (0000000000)
+0011: + 00 00 00 00 00 (0000000000)
+0012: + 00 00 00 00 00 (0000000000)
+MIX >
+@end example
+@end defun
+
+@defun mix-sover #t|#f
+The command @code{sover} takes as argument either the string @code{T} or
+the string @code{F}, to set, respectively, the overflow toggle to true
+or false. Its Scheme counterpart, @code{mix-sover}, takes as argument
+a Scheme boolean value: @code{#t} (true) or @code{#f}.
+@end defun
+
+For the remaining functions, you simply must take into account that when
+the command arguments are numerical, the corresponding Scheme function
+takes as arguments Scheme number literals. On the other hand, when the
+command argument is a string, the argument of its associated Scheme
+function will be a Scheme string. By way of example, the following
+invocations are pairwise equivalent:
+
+@example
+MIX > load ../samples/hello
+MIX > (mix-load "../samples/hello")
+
+MIX > next 5
+MIX > (mix-next 5)
+@end example
+
+@node Hooks, Additional VM functions, mixvm wrappers, Scheme functions reference
+@subsection Hook functions
+
+Hooks are functions evaluated before or after executing a @code{mixvm}
+command (or its corresponding Scheme function wrapper), or after an
+explicit or conditional breakpoint is found during the execution of a
+MIX program. The following functions let you install hooks:
+
+@defun mix-add-pre-hook command hook
+Adds a function to the list of pre-hooks associated with the give
+@var{command}. @var{command} is a string naming the corresponding @code{mixvm}
+command, and @var{hook} is a function which takes a single argument: a
+string list of the commands arguments. The following scheme code defines
+a simple hook and associates it with the @code{run} command:
+
+@example
+(define run-hook
+  (lambda (args)
+    (display "argument list: ")
+    (display args)
+    (newline)))
+(mix-add-pre-hook "run" run-hook)
+@end example
+
+Pre-hooks are executed, in the order they are added, before invoking the
+corresponding command (or its associated Scheme wrapper function).
+@end defun
+
+@defun mix-add-post-hook command hook
+Adds a function to the list of pre-hooks associated with the give
+@var{command}. The arguments have the same meaning as in
+@code{mix-add-pre-hook}.
+@end defun
+
+@defun mix-add-global-pre-hook hook
+@defunx mix-add-global-post-hook hook
+Global pre/post hooks are executed before/after any @code{mixvm} command
+or function wrapper invocation. In this case, @var{hook} takes two
+arguments: a string with the name of the command being invoked, and a
+string list with its arguments.
+@end defun
+
+@defun mix-add-break-hook hook
+@defunx mix-add-cond-break hook
+Add a hook funtion to be executed when an explicit (resp. conditional)
+breakpoint is encountered during program execution. @var{hook} is a
+function taking two arguments: the source line number where the hook has
+occurred, and the current program counter value. The following code
+shows a simple definition and installation of a break hook:
+
+@example
+(define break-hook
+  (lambda (line address)
+    (display "Breakpoint at line ") (display line)
+    (display " and address ") (display address)
+    (newline)))
+(mix-add-break-hook break-hook)
+@end example
+
+Break hook functions are entirely implemented in Scheme using regular
+post-hooks for the @code{next} and @code{run} commands. If you are
+curious, you can check the Scheme source code at
+@file{@emph{prefix}/share/mdk/mixguile-vm-stat.scm} (where @emph{prefix}
+stands for your root install directory, usualy @code{/usr} or
+@code{/usr/local}.
+@end defun
+
+
+See @ref{Hook functions} for further examples on using hook functions.
+
+
+@node Additional VM functions,  , Hooks, Scheme functions reference
+@subsection Additional VM functions
+
+When writing non-trivial Scheme extensions using the MIX/Scheme library,
+you will probably need to evaluate the contents of the virtual machine
+components (registers, memory cells and so on). For instance, you may
+need to store the contents of the @code{A} register in a variable. The
+Scheme functions described so far are of no help: you can print the
+contents of @code{A} using @code{(mix-preg 'A)}, but you cannot define a
+variable containing the contents of @code{A}. To address this kind of
+problems, the MIX/Scheme library provides the following additional
+functions:
+
+@defun mixvm-status
+@defunx mix-vm-status
+Return the current status of the virtual machine, as a number
+(@code{mixvm-status}) or as a symbol (@code{mix-vm-status}). Posible
+return values are:
+@multitable {aamixvmaastatusaa} {aamixvmastatusaaaaaaa} {return valuesaaaaaaaaaaaaaaaaaaaaaaaaaa}
+@item @code{(mixvm-status)} @tab @code{(mix-vm-status)} @tab
+@item 0 @tab MIX_ERROR @tab Loading or execution error
+@item 1 @tab MIX_BREAK @tab Breakpoint encountered
+@item 2 @tab MIX_COND_BREAK @tab Conditional breakpoint
+@item 3 @tab MIX_HALTED @tab Execution terminated
+@item 4 @tab MIX_RUNNING @tab Execution stopped after @code{next}
+@item 5 @tab MIX_LOADED @tab Program successfully loaded
+@item 6 @tab MIX_EMPTY @tab No program loaded
+@end multitable
+@end defun
+
+@defun mix-vm-error?
+@defunx mix-vm-break?
+@defunx mix-vm-cond-break?
+@defunx mix-vm-halted?
+@defunx mix-vm-running?
+@defunx mix-vm-loaded?
+@defunx mix-vm-empty?
+Predicates asking whether the current virtual machine status is
+@code{MIX_ERROR}, @code{MIX_BREAK}, etc.
+@end defun
+
+@defun mix-reg register
+@defunx mix-set-reg! register value
+@code{mix-reg} evaluates to a number which is the contents of the
+specified @var{register}. @code{mix-set-reg} sets the contents of the
+given @var{register} to @var{value}. The register can be specified
+either as a string (@code{"A"}, @code{"X"}, etc.) or as a symbol
+(@code{'A}, @code{'X}, etc.). For instance,
+
+@example
+guile> (mix-reg 'A)
+2341
+guile> (mix-set-reg! "A" 2000)
+ok
+guile> (define reg-a (mix-reg 'A))
+guile> (display reg-a)
+2000
+guile>
+@end example
+@end defun
+
+@defun mix-cell cell_no
+@defunx mix-set-cell! cell_no value
+Evaluate and set the contents of the memory cell number
+@var{cell_no}. Both @var{cell_no} and @var{value} are Scheme numbers.
+@end defun
+
+@defun mix-loc
+Evaluates to the value of the location counter (i.e., the address of the
+next instruction to be executed).
+@end defun
+
+@defun mix-over
+@defunx mix-set-over! #t|#f
+@code{mix-over} evaluates to @code{#t} if the overflow toggle is set,
+and to @code{#f} otherwise. The value of the overflow toggle can be
+modified using @code{mix-set-over!}.
+@end defun
+
+@defun mix-cmp
+@defunx mix-set-cmp! 'L|'E|'G
+Evaluate and set the comparison flag. Possible values are the scheme
+symbols @code{L} (lesser), @code{E} (equal) and @code{G} (greater).
+@end defun
+
+@defun mix-up-time
+Evaluates to the current virtual machine uptime.
+@end defun
+
+@defun mix-lap-time
+Evaluates to the current virtual machine lapsed time, i.e., the time
+elapsed since the last @code{run} or @code{next} command.
+@end defun
+
+@defun mix-prog-time
+Evaluates to the total time spent executing the currently loaded program.
+@end defun
+
+@defun mix-prog-name
+Evaluates to a string containing the basename (without any leading path)
+of the currently loaded MIX program.
+@end defun
+
+@defun mix-prog-path
+Evaluates to a string containing the full path to the currently loaded
+MIX program.
+@end defun
+
+@defun mix-src-path
+Evaluates to a string containing the full path to the source file of the
+currently loaded MIX program.
+@end defun
+
+@defun mix-src-line [lineno]
+@defunx mix-src-line-no
+@code{mix-src-line-no} evaluates to the current source file number
+during the execution of a program.  @code{mix-src-line} evaluates to a
+string containing the source file line number @var{lineno}; when
+invoked without argument, it evaluates to @code{(mix-src-line
+(mix-src-line-no))}.
+@end defun
+
+@defun mix-ddir
+Evaluates to a string containing the full path of the current device
+directory.
+@end defun
diff --git a/doc/mdk_mixvm.texi b/doc/mdk_mixvm.texi
new file mode 100644
index 0000000..2e21289
--- /dev/null
+++ b/doc/mdk_mixvm.texi
@@ -0,0 +1,813 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2002, 2003, 2004
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_mixvm.texi,v 1.20 2005/09/19 21:29:42 jao Exp $
+
+@node mixvm, gmixvm, mixasm, Top
+@comment  node-name,  next,  previous,  up
+@chapter @code{mixvm}, the MIX computer simulator
+
+@cindex mixvm
+
+This chapter describes @code{mixvm}, the MIX computer
+simulator. @code{mixvm} is a command line interface programme which
+simulates the MIX computer (@pxref{The MIX computer}). It is able
+to run MIXAL programs (@pxref{MIXAL}) previously compiled with the MIX
+assembler (@pxref{mixasm}). The simulator allows inspection of the MIX
+computer components (registers, memory cells, comparison flag and overflow
+toggle), step by step execution of MIX programmes, and breakpoint
+setting to aid you in debugging your code. For a tutorial description of
+@code{mixvm} usage, @xref{Running the program}.
+
+@menu
+* Invocation::
+* Commands::                    Commands available in interactive mode.
+* Devices::                     MIX block devices implementation.
+@end menu
+
+@node Invocation, Commands, mixvm, mixvm
+@comment  node-name,  next,  previous,  up
+@section Invoking @code{mixvm}
+
+@code{mixvm} can be invoked with the following command line options
+(note that, following GNU's conventions, we provide a long option name
+for each available single letter switch):
+
+@example
+mixvm [-vhurdtq] [--version] [--help] [--usage] [--run] [--dump]
+      [--time] [--noinit]  [FILE[.mix]]
+@end example
+
+@noindent
+The meaning of these options is as follows:
+
+@defopt -v
+@defoptx --version
+Prints version and copyleft information and exits.
+@end defopt
+
+@defopt -h
+@defoptx --help
+@defoptx -u
+@defoptx --usage
+Prints a summary of available options and exits.
+@end defopt
+
+@defopt -r
+@defoptx --run
+Loads the specified @var{FILE} and executes it. After the program
+execution, @code{mixvm} exits. @var{FILE} must be the name of a binary
+@file{.mix} program compiled with @code{mixasm}. If your program does
+not produce any output, use the @code{-d} flag (see below) to peek at
+the virtual machine's state after execution.
+@end defopt
+
+@defopt -d
+@defoptx --dump
+This option must be used in conjuction with @code{-r}, and tells
+@code{mixvm} to print the value of the virtual machine's registers,
+comparison flag and overflow toggle after executing the program named
+@var{FILE}. See @xref{Non-interactive mode}, for sample usage.
+@end defopt
+
+@defopt -t
+@defoptx --time
+This option must be used in conjuction with @code{-r}, and tells
+@code{mixvm} to print virtual time statistics for the program's
+execution.
+@end defopt
+
+When run without the @code{-r} flag, @code{mixvm} enters its interactive
+mode, showing you a prompt like this one:
+
+@example
+MIX >
+@end example
+
+@noindent
+and waiting for your commands (@pxref{Commands}). If the
+optional @var{FILE} argument is given, the file @file{FILE.mix} will be
+loaded into the virtual machine memory before entering the interactive
+mode.
+
+The first time @code{mixvm} is invoked, a directory named @file{.mdk} is
+created in your home directory. It contains the @code{mixvm}
+configuration file, the command history file and (by default) the block
+devices files (@pxref{Devices}). Before showing you the command prompt,
+@code{mixvm} looks in the @file{~/.mdk} directory for a file named
+@code{mixguile.scm}; if it exists, it is read and evaluated by the
+embedded Guile interpreter (@pxref{Defining new functions}). You can use
+the @code{-q} command line option to skip this file loading:
+
+@defopt -q
+@defoptx --noinit
+Do not load the Guile initialisation file @code{~/.mdk/mixguile.scm} at
+startup.
+@end defopt
+
+@node Commands, Devices, Invocation, mixvm
+@comment  node-name,  next,  previous,  up
+@section Interactive commands
+
+You can enter the interactive mode of the MIX virtual machine by simply
+invoking @code{mixvm} without arguments. You will then be greeted by a shell
+prompt@footnote{The default command prompt, @samp{MIX > }, can be
+changed using the @code{prompt} command (@pxref{Configuration commands})}
+
+@example
+MIX >
+@end example
+
+@noindent
+which indicates that a new virtual machine has been initialised and is
+ready to execute your commands. As we have already mentioned, this
+command prompt offers you command line editing facilities which are
+described in the Readline user's manual (chances are that you are
+already familiar with these command line editing capabilities, as they
+are present in many GNU utilities, e.g. the @code{bash}
+shell)@footnote{The readline functionality will be available if you have
+compiled @sc{mdk} with readline support, i.e., if GNU readline is
+installed in your system. This is ofte the case in GNU/Linux and BSD
+systems}. In a nutshell, readline provides command completion using the
+@kbd{TAB} key and command history using the cursor keys. A history file
+containing the last commands typed in previous sessions is stored in the
+@sc{mdk} configuration directory (@file{~/.mdk}).
+
+As a beginner, your best friend will be the @code{help} command, which
+shows you a summary of all available MIX commands and their usage; its
+syntax is as follows:
+
+@deffn {@code{mixvm} command} help [command]
+Prints a short description of the given @var{command} and its usage. If
+@var{command} is omitted, @code{help} prints the short description for
+all available commands.
+@end deffn
+
+@menu
+* File commands::               Loading and executing programs.
+* Debug commands::              Debugging programs.
+* State commands::              Inspecting the virtual machine state.
+* Configuration commands::      Changing and storing mixvm settings.
+* Scheme commands::
+@end menu
+
+@node File commands, Debug commands, Commands, Commands
+@subsection File commands
+
+You have at your disposal a series of commands that let you load and
+execute MIX executable files, as well as manipulate MIXAL source files:
+
+@deffn {file command} load file[.mix]
+This command loads a binary file, @var{file.mix} into the virtual
+machine memory, and positions the program counter at the beginning of
+the loaded program. This address is indicated in the MIXAL source file
+as the operand of the @code{END} pseudoinstruction. Thus, if your
+@file{sample.mixal} source file contains the line:
+
+@example
+     END 3000
+@end example
+
+@noindent
+and you compile it with @code{mixasm} to produce the binary file
+@file{sample.mix}, you will load it into the virtual machine as follows:
+
+@example
+MIX > load sample
+Program loaded. Start address: 3000
+MIX >
+@end example
+
+@end deffn
+
+@deffn {file command} run [file[.mix]]
+When executed without argument, this command initiates or resumes
+execution of instructions from the current program counter
+address. Therefore, issuing this command after a successful @code{load},
+will run the loaded program until either a @code{HLT} instruction or a
+breakpoint is found. If you provide a MIX filename as argument, the
+given file will be loaded (as with @code{load} @var{file}) and
+executed. If @code{run} is invoked again after program execution
+completion (i.e., after the @code{HLT} instruction has been found in a
+previous run), the program counter is repositioned and execution starts
+again from the beginning (as a matter of fact, a @code{load} command
+preserving the currently set breakpoints is issued before resuming
+execution).
+@end deffn
+
+@deffn {file command} edit [file[.mixal]]
+The source file @var{file.mixal} is edited using the editor defined in
+the environment variable @var{MDK_EDITOR}. If this variable is not set,
+the following ones are tried out in order: @var{X_EDITOR}, @var{EDITOR}
+and @var{VISUAL}. If invoked without argument, the source file for the
+currently loaded MIX file is edited. The command used to edit source
+files can also be configured using the @code{sedit} command
+(@pxref{Configuration commands}).
+@end deffn
+
+@deffn {file command} compile file[.mixal]
+The source file @var{file.mixal} is compiled (with debug information
+enabled) using @code{mixasm}. If invoked without argument, the source
+file for the currently loaded MIX file is recompiled. The compilation
+command can be set using the @code{sasm} command (@pxref{Configuration
+commands}).
+@end deffn
+
+@deffn {file command} pprog
+@deffnx {file command} psrc
+Print the path of the currently loaded MIX program and its source file:
+
+@example
+MIX > load ../samples/primes
+Program loaded. Start address: 3000
+MIX > pprog
+../samples/primes.mix
+MIX > psrc
+/home/jao/projects/mdk/gnu/samples/primes.mixal
+MIx>
+@end example
+@end deffn
+
+Finally, you can use the @code{quit} command to exit @code{mixvm}:
+
+@deffn {file command} quit
+Exit @code{mixvm}, saving the current configuration parameters in
+@file{~/.mdk/mixvm.config}.
+@end deffn
+
+
+@node Debug commands, State commands, File commands, Commands
+@subsection Debug commands
+
+Sequential execution of loaded programs can be interrupted using the
+following debug commands:
+
+@deffn {debug command} next [ins_number]
+This command causes the virtual machine to fetch and execute  up to
+@var{ins_number} instructions, beginning from the current program
+counter position. Execution is interrupted either when the specified
+number of instructions have been fetched or a breakpoint is found,
+whatever happens first. If run without arguments, one instruction is
+executed. If @code{next} is invoked again after program execution
+completion (i.e., after the @code{HLT} instruction has been found in a
+previous run), the program counter is repositioned and execution starts
+again from the beginning (as a matter of fact, a @code{load} command
+preserving the currently set breakpoints is issued before resuming
+execution).
+@end deffn
+
+@deffn {debug command} sbp line_number
+@deffnx {debug command} cbp line_no
+Sets a breakpoint at the specified source file line number. If the line
+specified corresponds to a command or to a MIXAL pseudoinstruction which
+does not produce a MIX instruction in the binary file (such as
+@code{ORIG} or @code{EQU}) the breakpoint is set at the first source
+code line giving rise to a MIX instruction after the specified
+one. Thus, for our sample @file{hello.mixal} file:
+
+@example
+*                                                        (1)
+* hello.mixal: say 'hello world' in MIXAL                (2)
+*                                                        (3)
+* label ins    operand     comment                       (4)
+TERM    EQU    19          the MIX console device number (5)
+        ORIG   1000        start address                 (6)
+START   OUT    MSG(TERM)   output data at address MSG    (7)
+...
+@end example
+
+@noindent
+trying to set a breakpoint at line 5, will produce the following result:
+
+@example
+MIX > sbp 5
+Breakpoint set at line 7
+MIX >
+@end example
+
+@noindent
+since line 7 is the first one compiled into a MIX instruction (at
+address 3000).
+
+The command @code{cbp} clears a (previously set) breakpoint at the given
+source file line.
+@end deffn
+
+@deffn {debug command} spba address
+@deffnx {debug command} cbpa address
+Sets a breakpoint at the given memory @var{address}. The argument must
+be a valid MIX memory address, i.e., it must belong into the range
+@w{[0-3999]}. Note that no check is performed to verify that the
+specified address is reachable during program execution. No debug
+information is needed to set a breakpoint by address with @code{sbpa}.
+The command @code{cbpa} clears a (previously set) breakpoint at the
+given memory address.
+@end deffn
+
+@deffn {debug command} sbpr A | X | J | Ii
+@deffnx {debug command} cbpr A | X | J | Ii
+Sets a conditional breakpoint on the specified register change. For
+instance,
+
+@example
+sbpr I1
+@end example
+
+@noindent
+will cause an interruption during program execution whenever the
+contents or register @code{I1} changes. A previously set breakpoint is
+cleared using the @code{cbpr} command.
+@end deffn
+
+@deffn {debug command} sbpm address
+@deffnx {debug command} cbpm address
+Sets a conditional breakpoint on the specified memory cell change. The
+argument must be a valid MIX memory address, i.e., it must belong into
+the range @w{[0-3999]}. For instance,
+
+@example
+sbpm 1000
+@end example
+
+@noindent
+will cause an interruption during program execution whenever the
+contents or of the memory cell number 1000 changes. A previously set
+breakpoint is cleared using the @code{cbpm} command.
+@end deffn
+
+@deffn {debug command} sbpo
+@deffnx {debug command} cbpo
+Sets/clears a conditional breakpoint on overflow toggle change.
+@end deffn
+
+@deffn {debug command} sbpc
+@deffnx {debug command} cbpc
+Sets/clears a conditional breakpoint on comparison flag change.
+@end deffn
+
+@deffn {debug command} cabp
+Clears all currently set breakpoints.
+@end deffn
+
+@deffn {debug command} psym [symbol_name]
+MIXAL programs can define symbolic constants, using either the
+@code{EQU} pseudoinstruction or a label at the beginning of a
+line. Thus, in the program fragment
+
+@example
+VAR     EQU  2168
+        ORIG 4000
+START   LDA  VAR
+@end example
+
+@noindent
+the symbol @code{VAR} stands for the value 2168, while @code{START} is
+assigned the value 4000. The symbol table can be consulted from
+the @code{mixvm} command line using @code{psym} followed by the name of
+the symbol whose contents you are interested in. When run without
+arguments, @code{psym} will print all defined symbols and their values.
+@end deffn
+
+The virtual machine can also show you the instructions it is executing,
+using the following commands:
+
+@deffn {debug command} strace [on|off]
+@code{strace on} enables instruction tracing. When tracing is enabled,
+each time the virtual machine executes an instruction (due to your
+issuing a @code{run} or @code{next} command), it is printed in its
+canonical form (that is, with all expressions evaluated to their
+numerical values) and, if the program was compiled with debug
+information, as it was originally typed in the MIXAL source
+file. Instruction tracing is disabled with @code{strace off}
+command. A typical tracing session could be like this:
+
+@example
+MIX > strace on
+MIX > next
+3000: [OUT	3002,0(2:3)]	START	OUT	MSG(TERM)
+MIXAL HELLO WORLD
+Elapsed time: 1 /Total program time: 1 (Total uptime: 1)
+MIX > next
+3001: [HLT	0,0]		HLT
+End of program reached at address 3002
+Elapsed time: 10 /Total program time: 11 (Total uptime: 11)
+MIX > strace off
+MIX >
+@end example
+@noindent
+The executed instruction, as it was translated, is shown between square
+brackets after the memory address, and, following it, you can see the
+actual MIXAL code that was compiled into the executed instruction. The
+tracing behaviour is stored as a configuration parameter in @file{~/.mdk}.
+@end deffn
+
+@deffn {debug command} pline [LINE_NUMBER]
+Prints the requested source line (or the current one if
+@var{line_number} is omitted:
+
+@example
+MIX > load ../samples/hello
+Program loaded. Start address: 3000
+MIX > pline
+Line 5: START       OUT   MSG(TERM)
+MIX > pline 6
+Line 6:             HLT
+MIX >
+@end example
+@end deffn
+
+@deffn {debug command} pbt [INS_NUMBER]
+This command prints a backtrace of executed instructions. Its optional
+argument @var{ins_number} is the number of instructions to print. If it
+is omitted or equals zero, all executed instructions are printed. For
+instance, if you compile and load the following program (@file{bt.mixal}):
+
+@example
+    ORIG 0
+BEG JMP *+1
+    JMP *+1
+FOO JMP BAR
+BAR HLT
+    END BEG
+@end example
+
+@noindent
+you could get the following traces:
+
+@example
+MIX > load bt
+Program loaded. Start address: 0
+MIX > next
+MIX > pbt
+#0      BEG     in bt.mixal:2
+MIX > next
+MIX > pbt
+#0      1       in bt.mixal:3
+#1      BEG     in bt.mixal:2
+MIX > run
+Running ...
+... done
+MIX > pbt 3
+#0      BAR     in bt.mixal:5
+#1      FOO     in bt.mixal:4
+#2      1       in bt.mixal:3
+MIX > pbt
+#0      BAR     in bt.mixal:5
+#1      FOO     in bt.mixal:4
+#2      1       in bt.mixal:3
+#3      BEG     in bt.mixal:2
+MIX >
+@end example
+
+Note that the executed instruction trace gives you the label of the
+executed line or, if it has no label, its address.
+@end deffn
+
+As you have probably observed, @code{mixvm} prints timing statistics
+when running programs. This behaviour can be controlled using the
+@code{stime} command (@pxref{Configuration commands}).
+
+@code{mixvm} is also able of evaluating w-expressions
+(@pxref{W-expressions}) using the following command:
+
+@deffn {debug command} weval WEXP
+Evaluates the given w-expression, @var{WEXP}. The w-expression can
+contain any currently defined symbol. For instance:
+
+@example
+MIX > psym START
++ 00 00 00 46 56 (0000003000)
+MIX > weval START(0:1),START(3:4)
++ 56 00 46 56 00 (0939716096)
+MIX >
+@end example
+@end deffn
+
+New symbols can be defined using the @code{ssym} command:
+
+@deffn {debug command} ssym SYM WEXP
+Defines the symbol named @var{SYM} with the value resulting from
+evaluating @var{WEXP}, an w-expression. The newly defined symbol can be
+used in subsequent @code{weval} commands, as part of the expression to
+be evaluated. E.g.,
+
+@example
+MIX > ssym S 2+23*START
++ 00 00 18 19 56 (0000075000)
+MIX > psym S
++ 00 00 18 19 56 (0000075000)
+MIX > weval S(3:4)
++ 00 00 19 56 00 (0000081408)
+MIX >
+@end example
+@end deffn
+
+Finally, if you want to discover which is the decimal value of a MIX
+word expressed as five bytes plus sign, you can use
+
+@deffn {debug command} w2d WORD
+Computes the decimal value of the given word. @var{WORD} must be
+expressed as a sign (+/-) followed by five space-delimited, two-digit
+decimal values representing the five bytes composing the word. The
+reverse operation (showing the word representation of a decimal value)
+can be accomplished with @code{weval}. For instance:
+
+@example
+MIX > w2d - 01 00 00 02 02
+-16777346
+MIX > weval -16777346
+- 01 00 00 02 02 (0016777346)
+MIX >
+@end example
+@end deffn
+
+@node State commands, Configuration commands, Debug commands, Commands
+@subsection State commands
+
+Inspection and modification of the virtual machine state (memory,
+registers, overflow toggle and comparison flag contents) is accomplished
+using the following commands:
+
+@deffn {state command} pstat
+This commands prints the current virtual machine state, which can be one
+of the following:
+@itemize @minus
+@item
+No program loaded
+@item
+Program successfully loaded
+@item
+Execution stopped (@code{next} executed)
+@item
+Execution stopped: breakpoint encountered
+@item
+Execution stopped: conditional breakpoint encountered
+@item
+Program successfully terminated
+@end itemize
+@end deffn
+
+@deffn {state command} pc
+Prints the current value of the program counter, which stores the
+address of the next instruction to be executed in a non-halted program.
+@end deffn
+
+@deffn {state command} sreg A | X | J | I[1-6] value
+@deffnx {state command} preg [A | X | J | I[1-6]]
+@deffnx {state command} pall
+@code{preg} prints the contents of a given MIX register. For instance,
+@w{@code{preg} @var{A}} will print the contents of the A-register. When
+invoked without arguments, all registers shall be printed:
+
+@example
+MIX > preg
+rA: - 00 00 00 00 35 (0000000035)
+rX: + 00 00 00 15 40 (0000001000)
+rJ: + 00 00 (0000)
+rI1: + 00 00 (0000)	rI2: + 00 00 (0000)
+rI3: + 00 00 (0000)	rI4: + 00 00 (0000)
+rI5: + 00 00 (0000)	rI6: + 00 00 (0000)
+MIX >
+@end example
+
+As you can see in the above sample, the contents is printed as the sign
+plus the values of the MIX bytes stored in the register and, between
+parenthesis, the decimal representation of its module.
+
+@code{pall} prints the contents of all registers plus the comparison
+flag and overflow toggle.
+
+Finally, @code{sreg} Sets the contents of the given register to
+@var{value}, expressed as a decimal constant. If @var{value} exceeds the
+maximum value storable in the given register, @code{VALUE mod
+MAXIMU_VALUE} is stored, e.g.
+
+@example
+MIX > sreg I1 1000
+MIX > preg I1
+rI1: + 15 40 (1000)
+MIX > sreg I1 1000000
+MIX > preg I1
+rI1: + 09 00 (0576)
+MIX >
+@end example
+
+@end deffn
+
+
+@deffn {state command} pflags
+@deffnx {state command} scmp E | G | L
+@deffnx {state command} sover F | T
+@code{pflags} prints the value of the comparison flag and overflow
+toggle of the virtual machine, e.g.
+
+@example
+MIX > pflags
+Overflow: F
+Cmp: E
+MIX >
+@end example
+
+@noindent
+The values of the overflow toggle are either @var{F} (false) or @var{T}
+(true), and, for the comparison flag, @var{E}, @var{G}, @var{L} (equal,
+greater, lesser). @code{scmp} and @code{sover} are setters of the
+comparison flag and overflow toggle values.
+@end deffn
+
+@deffn {state command} pmem from[-to]
+@deffnx {state command} smem address value
+@code{pmem} prints the contents of memory cells in the address range
+@w{[@var{FROM}-@var{TO}]}. If the upper limit @var{to} is omitted, only
+the contents of the memory cell with address @var{FROM} is printed, as
+in
+
+@example
+MIX > pmem 3000
+3000: + 46 58 00 19 37 (0786957541)
+MIX >
+@end example
+
+The memory contents is displayed both as the set of five MIX bytes plus
+sign composing the stored MIX word and, between parenthesis, the decimal
+representation of the module of the stored value.
+
+@code{smem} sets the content of the memory cell with address
+@var{address} to @var{value}, expressed as a decimal constant.
+
+@end deffn
+
+@node Configuration commands, Scheme commands, State commands, Commands
+@subsection Configuration commands
+
+This section describes commands that allow you to configure the virtual
+machine behaviour. This configuration is stored in the @sc{mdk}
+directory @file{~/.mdk}.
+
+As you can see in their description, some commands print, as a side
+effect, informational messages to the standard output (e.g. @code{load}
+prints a message telling you the loaded program's start address): these
+messages can be enabled/disabled using @code{slog}:
+
+@deffn {config command} slog on|off
+Turns on/off the logging of informational messages. Note that error
+messages are always displayed, as well as state messages required using
+commands prefixed with @code{p} (@code{preg}, @code{pmem} and the like).
+@end deffn
+
+@deffn {config command} stime  on|off
+@deffnx {config command} ptime
+The @code{stime} command (un)sets the printing of timing statistics, and
+@code{ptime} prints their current value:
+
+@example
+MIX > ptime
+Elapsed time: 10 /Total program time: 11 (Total uptime: 11)
+MIX >
+@end example
+@end deffn
+
+@deffn {config command} sedit TEMPLATE
+@deffnx {config command} pedit
+@code{sedit} sets the command to be used to edit MIXAL source files with
+the @code{edit} command. @var{TEMPLATE} must contain the control
+characters @code{%s} to mark the place where the source's file name will
+be inserted. For instance, if you type
+
+@example
+MIX > sedit emacsclient %s
+MIX >
+@end example
+
+issuing the @code{mixvm} command @w{@code{edit foo.mixal}} will invoke
+the operating system command @w{@code{emacsclient foo.mixal}}.
+
+@code{pedit} prints the current value of the edit command template.
+
+@end deffn
+
+@deffn {config command} sasm TEMPLATE
+@deffnx {config command} pasm
+@code{sasm} sets the command to be used to compile MIXAL source files with
+the @code{compile} command. @var{template} must contain the control
+characters @code{%s} to mark the place where the source's file name will
+be inserted. For instance, if you type
+
+@example
+MIX > sasm mixasm -l %s
+MIX >
+@end example
+
+issuing the @code{mixvm} command @w{@code{compile foo.mixal}} will invoke
+the operating system command @w{@code{mixasm -l foo.mixal}}.
+
+@code{pasm} prints the current value of the compile command template.
+
+@end deffn
+
+@deffn {config command} sddir DIRNAME
+@deffnx {config command} pddir
+MIX devices (@pxref{Devices}) are implemented as regular files stored,
+by default, inside @file{~/.mdk}. The @code{sddir} command lets you
+specify an alternative location for storing these device files, while
+@code{pddir} prints the current device directory.
+@end deffn
+
+Finally, you can change the default command prompt, @samp{MIX > },
+using the @code{prompt} command:
+
+@deffn {config command} prompt PROMPT
+Changes the command prompt to @var{prompt}. If you want to include
+white space(s) at the end of the new prompt, bracket @var{prompt} using
+double quotes (e.g., @code{prompt ">> "}).
+@end deffn
+
+@node Scheme commands,  , Configuration commands, Commands
+@subsection Scheme commands
+
+If you have compiled @sc{mdk} with @code{libguile} support
+(@pxref{Special configure flags}), @code{mixvm} will start and
+initialise an embedded Guile Scheme interpret when it is invoked. That
+means that you have at your disposal, at @code{mixvm}'s command prompt,
+all the Scheme primitives described in @ref{Using mixguile} and
+@ref{mixguile}, as well as any other function or hook that you have
+defined in the initialisation file @file{~/.mdk/mixguile.scm}. To
+evaluate a Scheme function, simply type it at the @code{mixvm} command
+prompt (see @ref{Using Scheme in mixvm and gmixvm} for a
+sample). Compared to the @code{mixguile} program, this has only one
+limitation: the expressions used in @code{mixvm} cannot span more than
+one line. You can get over this inconvenience writing your multiline
+Scheme expressions in a file and loading it using the @code{scmf}
+command:
+
+@deffn {scheme command} scmf FILE_NAME
+Loads the given Scheme file and evaluates it using the embedded Guile
+interpreter.
+@end deffn
+
+
+@node Devices,  , Commands, mixvm
+@section MIX block devices
+
+The MIX computer comes equipped with a set of block devices for
+input-output operations (@pxref{Input-output operators}). @code{mixvm}
+implements these block devices as disk files, with the exception of
+block device no. 19 (typewriter terminal) which is redirected to
+standard input/output. When you request an output operation on any other
+(output) device, a file named according to the following table will be
+created, and the specified MIX words will be
+written to the file in binary form (for binary devices) or in ASCII (for
+char devices). Files corresponding to input block devices should be
+created and filled beforehand to be used by the MIX virtual machine (for
+input-output devices this creation can be accomplished by a MIXAL
+program writing to the device the required data, or, if you prefer, with
+your favourite editor). The device files are stored, by default, in the
+directory @file{~/.mdk}; this location can be changed using the
+@code{mixvm} command @code{devdir} (@pxref{Configuration commands}).
+
+@multitable {the device name} { xx-xx } {filename[x-x].dev} {bin  i/o/char }
+@item @emph{Device}  @tab @emph{No.} @tab @emph{filename} @tab @emph{type and block size}
+@item Tape @tab 0-7 @tab @file{tape[0-7].dev} @tab bin i/o - 100 words
+@item Disks @tab 8-15 @tab @file{disk[0-7].dev} @tab bin i/o - 100 words
+@item Card reader @tab 16 @tab @file{cardrd.dev} @tab char in - 16 words
+@item Card writer @tab 17 @tab @file{cardwr.dev} @tab char out - 16 words
+@item Line printer @tab 18 @tab @file{printer.dev} @tab char out - 24 words
+@item Terminal @tab 19 @tab @code{stdin/stdout} @tab char i/o - 14 words
+@item Paper tape @tab 20 @tab @file{paper.dev} @tab char in - 14 words
+@end multitable
+
+Devices of type @i{char} are stored as ASCII files, using one line per
+block. For instance, since the card reader has blocks of size 16, that
+is, 80 characters, it will be emulated by an ASCII file consisting of
+lines with length 80. If the reader finds a line with less than the
+required number of characters, it pads the memory with zeroes (MIX
+character 'space') to complete the block size.
+
+Note that the virtual machine automatically converts between the MIX and
+ASCII character encodings, so that you can manipulate char device files
+with any ASCII editor. In addition, the reader is not case-sensitive,
+i.e., it automatically converts lowercase letters to their uppercase
+counterparts (since the MIX character set does not include the former).
+
+The typewriter (device no. 19) lets you use the standard input and
+output in your MIXAL programs. For instance, here is a simple 'echo'
+program:
+
+@example
+* simple echo program
+TERM    EQU     19          the typewriter device
+BUF     EQU     500         input buffer
+        ORIG    1000
+START   IN      BUF(TERM)   read a block (70 chars)
+        OUT     BUF(TERM)   write the read chars
+        HLT
+        END     START
+@end example
+
+@noindent Input lines longer than 70 characters (14 words) are trimmed.
+On the other hand, if you type less than a block of characters,
+whitespace (MIX character zero) is used as padding.
+
diff --git a/doc/mdk_tut.texi b/doc/mdk_tut.texi
new file mode 100644
index 0000000..0fabe89
--- /dev/null
+++ b/doc/mdk_tut.texi
@@ -0,0 +1,1319 @@
+@c -*-texinfo-*-
+@c This is part of the GNU MDK Reference Manual.
+@c Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005
+@c   Free Software Foundation, Inc.
+@c See the file mdk.texi for copying conditions.
+
+@c $Id: mdk_tut.texi,v 1.14 2005/09/20 00:26:00 jao Exp $
+
+@node MIX and MIXAL tutorial, Getting started, Installing MDK, Top
+@comment  node-name,  next,  previous,  up
+@chapter MIX and MIXAL tutorial
+@cindex MIX
+@cindex MIXAL
+
+In the book series @cite{The Art of Computer Programming}, by D. Knuth,
+a virtual computer, the MIX, is used by the author (together with the
+set of binary instructions that the virtual CPU accepts) to illustrate
+the algorithms and skills that every serious programmer should
+master. Like any other real computer, there is a symbolic assembler
+language that can be used to program the MIX: the MIX assembly language,
+or MIXAL for short.  In the following subsections you will find a tutorial
+on these topics, which will teach you the basics of the MIX architecture
+and how to program a MIX computer using MIXAL.
+
+@menu
+* The MIX computer::            Architecture and instruction set
+                                of the MIX computer.
+* MIXAL::                       The MIX assembly language.
+@end menu
+
+@node The MIX computer, MIXAL, MIX and MIXAL tutorial, MIX and MIXAL tutorial
+@comment  node-name,  next,  previous,  up
+@section The MIX computer
+
+In this section, you will find a description of the MIX computer,
+its components and instruction set.
+
+@menu
+* MIX architecture::
+* MIX instruction set::
+@end menu
+
+@node MIX architecture, MIX instruction set, The MIX computer, The MIX computer
+@comment  node-name,  next,  previous,  up
+@subsection MIX architecture
+@cindex byte
+@cindex MIX byte
+@cindex word
+@cindex MIX word
+@cindex MIX architecture
+@cindex MIX computer
+@cindex register
+@cindex MIX register
+@cindex field specification
+@cindex fspec
+@cindex instruction
+@cindex MIX instruction
+@cindex address
+@cindex memory cell
+@cindex cell
+@cindex memory
+@cindex index
+
+The basic information storage unit in the MIX computer is the
+@dfn{byte}, which stores positive values in the range 0-63 . Note that a
+MIX byte can be then represented as 6 bits, instead of the common 8 bits
+for a @emph{regular} byte. Unless otherwise stated, we shall use the
+word @dfn{byte} to refer to a MIX 6-bit byte.
+
+A MIX @dfn{word} is defined as a set of 5 bytes plus a sign. The bytes
+within a word are numbered from 1 to 5, being byte number one the most
+significant one. The sign is denoted by index 0. Graphically,
+
+@example
+ -----------------------------------------------
+|   0   |   1   |   2   |   3   |   4   |   5   |
+ -----------------------------------------------
+|  +/-  | byte  | byte  | byte  | byte  | byte  |
+ -----------------------------------------------
+@end example
+@noindent
+Sample MIX words are @samp{- 12 00 11 01 63} and @samp{+ 12 11 34 43
+00}.
+
+You can refer to subfields within a word using a @dfn{field
+specification} or @dfn{fspec} of the form ``(@var{L}:@var{R})'', where
+@var{L} denotes the first byte, and @var{R} the last byte of the
+subfield.
+When @var{L} is zero, the subfield includes the word's
+sign. An fspec can also be represented as a single value @code{F}, given
+by @code{F = 8*L + R} (thus the fspec @samp{(1:3)}, denoting the first
+three bytes of a word, is represented by the integer 11).
+
+The MIX computer stores information in @dfn{registers}, that can store
+either a word or two bytes and sign (see below), and @dfn{memory cells},
+each one containing a word. Specifically, the MIX computer has 4000
+memory cells with addresses 0 to 3999 (i.e., two bytes are enough to
+address a memory cell) and the following registers:
+
+@cindex rA
+@cindex rX
+@cindex rJ
+@cindex rIn
+@cindex register
+
+@table @asis
+@item @code{rA}
+A register. General purpose register holding a word. Usually its
+contents serves as the operand of arithmetic and storing instructions.
+@item @code{rX}
+X register. General purpose register holding a word. Often it acts as an
+extension or a replacement of @samp{rA}.
+@item @code{rJ}
+J (jump) register. This register stores positive two-byte values,
+usually representing a jump address.
+@item @code{rI1}, @code{rI2}, @code{rI3}, @code{rI4}, @code{rI5}, @code{rI6}
+Index registers. These six registers can store a signed two-byte
+value. Their contents are used as indexing values for the computation of
+effective memory addresses.
+@end table
+
+@cindex @sc{ov}
+@cindex @sc{cm}
+@cindex @code{un}
+@cindex overflow toggle
+@cindex comparison indicator
+@cindex input-output devices
+@noindent
+In addition, the MIX computer contains:
+
+@itemize @minus
+@item
+An @dfn{overflow toggle} (a single bit with values @dfn{on} or
+@dfn{off}). In this manual, this toggle is denoted @sc{ov}.
+@item
+A @dfn{comparison indicator} (having three values: @dfn{EQUAL},
+@dfn{GREATER} or @dfn{LESS}). In this manual, this indicator is denoted
+@sc{cm}, and its possible values are abbreviated as @dfn{E}, @dfn{G} and
+@dfn{L}.
+@item
+Input-output block devices. Each device is labelled as @code{un}, where
+@code{n} runs from 0 to 20. In Knuth's definition, @code{u0} through
+@code{u7} are magnetic tape units, @code{u8} through @code{15} are disks
+and drums, @code{u16} is a card reader, @code{u17} is a card writer,
+@code{u18} is
+a line printer and, @code{u19} is a typewriter terminal, and @code{u20},
+a paper tape. Our implementation maps these devices to disk files,
+except for @code{u19}, which represents the standard output.
+@end itemize
+
+As noted above, the MIX computer communicates with the external world by
+a set of input-output devices which can be ``connected'' to it. The
+computer interchanges information using blocks of words whose length
+depends on the device at hand (@pxref{Devices}). These words are
+interpreted by the device either as binary information (for devices
+0-16), or as representing printable characters (devices 17-20). In the
+last case, each MIX byte is mapped onto a character according to the
+following table:
+
+@multitable  {00} {C} {00} {C} {00} {C} {00} {C}
+@item  00 @tab  @tab 01 @tab A @tab 02 @tab B @tab 03 @tab C
+@item  04 @tab D @tab 05 @tab E @tab 06 @tab F @tab 07 @tab G
+@item  08 @tab H @tab 09 @tab I @tab 10 @tab ~ @tab 11 @tab J
+@item  12 @tab K @tab 13 @tab L @tab 14 @tab M @tab 15 @tab N
+@item  16 @tab O @tab 17 @tab P @tab 18 @tab Q @tab 19 @tab R
+@item  20 @tab [ @tab 21 @tab # @tab 22 @tab S @tab 23 @tab T
+@item  24 @tab U @tab 25 @tab V @tab 26 @tab W @tab 27 @tab X
+@item  28 @tab Y @tab 29 @tab Z @tab 30 @tab 0 @tab 31 @tab 1
+@item  32 @tab 2 @tab 33 @tab 3 @tab 34 @tab 4 @tab 35 @tab 5
+@item  36 @tab 6 @tab 37 @tab 7 @tab 38 @tab 8 @tab 39 @tab 9
+@item  40 @tab . @tab 41 @tab , @tab 42 @tab ( @tab 43 @tab )
+@item  44 @tab + @tab 45 @tab - @tab 46 @tab * @tab 47 @tab /
+@item  48 @tab = @tab 49 @tab $ @tab 50 @tab < @tab 51 @tab >
+@item  52 @tab @@ @tab 53 @tab ; @tab 54 @tab : @tab 55 @tab '
+@end multitable
+@noindent
+The value 0 represents a whitespace. The characters @code{~}, @code{[} and
+@code{#} correspond to symbols not representable as ASCII characters
+(uppercase delta, sigma and gamma, respectively), and byte values 56-63
+have no associated character.
+
+Finally, the MIX computer features a virtual CPU which controls the
+above components, and which is able to execute a rich set of
+instructions (constituting its machine language, similar to those
+commonly found in real CPUs), including arithmetic, logical, storing,
+comparison and jump instructions. Being a typical von Neumann computer,
+the MIX CPU fetchs binary instructions from memory sequentially (unless
+a jump instruction is found), and stores the address of the next
+instruction to be executed in an internal register called @dfn{location
+counter} (also known as program counter in other architectures).
+
+The next section, @xref{MIX instruction set}, gives a complete description
+of the available MIX binary instructions.
+
+@node MIX instruction set,  , MIX architecture, The MIX computer
+@comment  node-name,  next,  previous,  up
+@subsection MIX instruction set
+@cindex instruction set
+
+The following subsections fully describe the instruction set of the MIX
+computer. We begin with a description of the structure of binary
+instructions and the notation used to refer to their subfields. The
+remaininig subsections are devoted to describing the actual instructions
+available to the MIX programmer.
+
+@menu
+* Instruction structure::
+* Loading operators::
+* Storing operators::
+* Arithmetic operators::
+* Address transfer operators::
+* Comparison operators::
+* Jump operators::
+* Input-output operators::
+* Conversion operators::
+* Shift operators::
+* Miscellaneous operators::
+* Execution times::
+@end menu
+
+@node Instruction structure, Loading operators, MIX instruction set, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Instruction structure
+
+MIX @dfn{instructions} are codified as words with the following subfield
+structure:
+
+@multitable @columnfractions .15 .20 .65
+@item @emph{Subfield} @tab @emph{fspec} @tab @emph{Description}
+@item ADDRESS @tab (0:2)
+@tab The first two bytes plus sign are the @dfn{address} field. Combined
+with the INDEX field, denotes the memory address to be used by the
+instruction.
+@item INDEX @tab (3:3)
+@tab The third byte is the @dfn{index}, normally used for indexing the
+address@footnote{The actual memory address the instruction refers to, is
+obtained by adding to ADDRESS the value of the @samp{rI} register
+denoted by INDEX.}.
+@item MOD @tab (4:4)
+@tab Byte four is used either as an operation code modifier or as a field
+specification.
+@item OPCODE @tab (5:5)
+@tab The last (least significant) byte in the word denotes the operation
+code.
+@end multitable
+
+@noindent
+or, graphically,
+
+@example
+ ------------------------------------------------
+|   0   |   1   |   2   |   3   |   4   |   5    |
+ ------------------------------------------------
+|        ADDRESS        | INDEX |  MOD  | OPCODE |
+ ------------------------------------------------
+@end example
+
+For a given instruction, @samp{M} stands for
+the memory address obtained after indexing the ADDRESS subfield
+(using its INDEX byte), and @samp{V} is the contents of the
+subfield indicated by MOD of the memory cell with address @samp{M}. For
+instance, suppose that we have the following contents of MIX registers
+and memory cells:
+
+@example
+[rI2] = + 00 63
+[31] = - 10 11 00 11 22
+@end example
+@noindent
+where @samp{[n]} denotes the contents of the nth memory cell and
+@samp{[rI2]} the contents of register @samp{rI2}@footnote{In general,
+@samp{[X]} will denote the contents of entity @samp{X}; thus, by
+definition, @w{@samp{V = [M](MOD)}}.}.  Let us consider the binary
+instruction @w{@samp{I = - 00 32 02 11 10}}. For this instruction we
+have:
+
+@example
+ADDRESS = - 00 32 = -32
+INDEX = 02 = 2
+MOD = 11 = (1:3)
+OPCODE = 10
+
+M = ADDRESS + [rI2] = -32 + 63 = 31
+V = [M](MOD) = (- 10 11 00 11 22)(1:3) = + 00 00 10 11 00
+@end example
+
+Note that, when computing @samp{V} using a word and an fspec, we apply
+a left padding to the bytes selected by @samp{MOD} to obtain a
+complete word as the result.
+
+In the following subsections, we will
+assign to each MIX instruction a mnemonic, or symbolic name. For
+instance, the mnemonic of @samp{OPCODE} 10 is @samp{LD2}. Thus we can
+rewrite the above instruction as
+
+@example
+LD2  -32,2(1:3)
+@end example
+@noindent
+or, for a generic instruction:
+
+@example
+MNEMONIC  ADDRESS,INDEX(MOD)
+@end example
+@noindent
+Some instructions are identified by both the OPCODE and the MOD
+fields. In these cases, the MOD will not appear in the above symbolic
+representation. Also when ADDRESS or INDEX are zero, they can be
+omitted.  Finally, MOD defaults to (0:5) (meaning the
+whole word).
+
+@node Loading operators, Storing operators, Instruction structure, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Loading operators
+@cindex loading operators
+
+The following instructions are used to load memory contents into a
+register.
+
+@ftable @code
+@item LDA
+Put in rA the contents of cell no. M.
+OPCODE = 8, MOD = fspec. @code{rA <- V}.
+@item LDX
+Put in rX the contents of cell no. M.
+OPCODE = 15, MOD = fspec. @code{rX <- V}.
+@item LDi
+Put in rIi the contents of cell no. M.
+OPCODE = 8 + i, MOD = fspec. @code{rIi <- V}.
+@item LDAN
+Put in rA the contents of cell no. M, with opposite sign.
+OPCODE = 16, MOD = fspec. @code{rA <- -V}.
+@item LDXN
+Put in rX the contents of cell no. M, with opposite sign.
+OPCODE = 23, MOD = fspec. @code{rX <- -V}.
+@item LDiN
+Put in rIi the contents of cell no. M, with opposite sign.
+OPCODE = 16 + i, MOD = fspec. @code{rIi <- -V}.
+@end ftable
+
+In all the above load instructions the @samp{MOD} field selects the
+bytes of the memory cell with address @samp{M} which are loaded into the
+requisite register (indicated by the @samp{OPCODE}).  For instance, the
+word @w{@samp{+ 00 13 01 27 11}} represents the instruction
+
+@example
+LD3    13,1(3:3)
+ ^      ^ ^  ^
+ |      | |  |
+ |      | |   --- MOD = 27 = 3*8 + 3
+ |      |  --- INDEX = 1
+ |       --- ADDRESS = 00 13
+  --- OPCODE = 11
+@end example
+Let us suppose that, prior to this instruction execution, the state of
+the MIX computer is the following:
+
+@example
+[rI1] = - 00 01
+[rI3] = + 24 12
+[12] = - 01 02 03 04 05
+@end example
+@noindent
+As, in this case, @w{@samp{M = 13 + [rI1] = 12}}, we have
+
+@example
+V = [M](3:3) = (- 01 02 03 04 05)(3:3)
+  = + 00 00 00 00 03
+@end example
+@noindent
+(note that the specified subfield is left-padded with null bytes to
+complete a word). Hence, the MIX state, after the instruction execution,
+will be
+
+@example
+[rI1] = - 00 01
+[rI3] = + 00 03
+[12] = - 01 02 03 04 05
+@end example
+
+To further illustrate loading operators, the following table shows the
+contents of @samp{rX} after different @samp{LDX} instructions:
+
+@table @samp
+@item LDX 12(0:0)     [rX] = - 00 00 00 00 00
+@item LDX 12(0:1)     [rX] = - 00 00 00 00 01
+@item LDX 12(3:5)     [rX] = + 00 00 03 04 05
+@item LDX 12(3:4)     [rX] = + 00 00 00 03 04
+@item LDX 12(0:5)     [rX] = - 01 02 03 04 05
+@end table
+
+
+@node Storing operators, Arithmetic operators, Loading operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Storing operators
+@cindex storing operators
+
+The following instructions are the inverse of the load
+operations: they are used to store a subfield of a register
+into a memory location. Here, MOD represents the subfield of the memory
+cell that is to be overwritten with bytes from a register. These bytes
+are taken beginning by the rightmost side of the register.
+
+@ftable @code
+@item STA
+Store rA. OPCODE = 24, MOD = fspec. @code{V <- rA}.
+@item STX
+Store rX. OPCODE = 31, MOD = fspec. @code{V <- rX}.
+@item STi
+Store rIi. OPCODE = 24 + i, MOD = fspec. @code{V <- rIi}.
+@item STJ
+Store rJ. OPCODE = 32, MOD = fspec. @code{V <- rJ}.
+@item STZ
+Store zero. OPCODE = 33, MOD = fspec. @code{V <- 0}.
+@end ftable
+
+By way of example, consider the instruction @samp{STA 1200(2:3)}. It
+causes the MIX to fetch bytes no. 4 and 5 of register A and copy them to
+bytes 2 and 3 of memory cell no. 1200 (remember that, for these
+instructions, MOD specifies a subfield of @emph{the memory
+address}). The other bytes of the memory cell retain their
+values. Thus, if prior to the instruction execution we have
+
+@example
+[1200] = - 20 21 22 23 24
+[rA] = + 01 02 03 04 05
+@end example
+@noindent
+we will end up with
+
+@example
+[1200] = - 20 04 05 23 24
+[rA] = + 01 02 03 04 05
+@end example
+
+As a second example, @samp{ST2 1000(0)} will set the sign of
+@samp{[1000]} to that of @samp{[rI2]}.
+
+@node Arithmetic operators, Address transfer operators, Storing operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Arithmetic operators
+@cindex arithmetic operators
+
+The following instructions perform arithmetic operations between rA and
+rX register and memory contents.
+
+@ftable @code
+@item ADD
+Add and set OV if overflow. OPCODE = 1, MOD = fspec.
+@w{@code{rA <- rA +V}}.
+@item SUB
+Sub and set OV if overflow. OPCODE = 2, MOD = fspec.
+@w{@code{rA <- rA - V}}.
+@item MUL
+Multiply V times rA and store the 10-bytes product in rAX.
+OPCODE = 3, MOD = fspec. @w{@code{rAX <- rA x V}}.
+@item DIV
+rAX is considered a 10-bytes number, and it is divided by V.
+OPCODE = 4, MOD = fspec. @w{@code{rA <- rAX / V}}, @code{rX} <- reminder.
+@end ftable
+
+In all the above instructions, @samp{[rA]} is one of the operands
+of the binary arithmetic operation, the other being @samp{V} (that is,
+the specified subfield of the memory cell with address @samp{M}), padded
+with zero bytes on its left-side to complete a word. In multiplication
+and division, the register @samp{X} comes into play as a right-extension
+of the register @samp{A}, so that we are able to handle 10-byte numbers
+whose more significant bytes are those of @samp{rA} (the sign of this
+10-byte number is that of @samp{rA}: @samp{rX}'s sign is ignored).
+
+Addition and substraction of MIX words can give rise to overflows, since
+the result is stored in a register with room to only 5 bytes (plus
+sign). When this occurs, the operation result modulo @w{1,073,741,823}
+(the maximum value storable in a MIX word) is stored in @samp{rA}, and
+the overflow toggle is set to TRUE.
+
+@node Address transfer operators, Comparison operators, Arithmetic operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Address transfer operators
+@cindex address transfer operators
+
+In these instructions, @samp{M} (the address of the instruction after
+indexing) is used as a number instead of as the address of a memory
+cell. Consequently, @samp{M} can have any valid word value (i.e., it's
+not limited to the 0-3999 range of a memory address).
+
+@ftable @code
+@item ENTA
+Enter @samp{M} in [rA]. OPCODE = 48, MOD = 2. @code{rA <- M}.
+@item ENTX
+Enter @samp{M} in [rX]. OPCODE = 55, MOD = 2. @code{rX <- M}.
+@item ENTi
+Enter @samp{M} in [rIi]. OPCODE = 48 + i, MOD = 2. @code{rIi <- M}.
+@item ENNA
+Enter @samp{-M} in [rA]. OPCODE = 48, MOD = 3. @code{rA <- -M}.
+@item ENNX
+Enter @samp{-M} in [rX]. OPCODE = 55, MOD = 3. @code{rX <- -M}.
+@item ENNi
+Enter @samp{-M} in [rIi]. OPCODE = 48 + i, MOD = 3. @code{rIi <- -M}.
+@item INCA
+Increase [rA] by @samp{M}. OPCODE = 48, MOD = 0. @code{rA <- rA + M}.
+@item INCX
+Increase [rX] by @samp{M}. OPCODE = 55, MOD = 0. @code{rX <- rX + M}.
+@item INCi
+Increase [rIi] by @samp{M}. OPCODE = 48 + i, MOD = 0. @code{rIi <- rIi + M}.
+@item DECA
+Decrease [rA] by @samp{M}. OPCODE = 48, MOD = 1. @code{rA <- rA - M}.
+@item DECX
+Decrease [rX] by @samp{M}. OPCODE = 55, MOD = 1. @code{rX <- rX - M}.
+@item DECi
+Decrease [rIi] by @samp{M}. OPCODE = 48 + i, MaOD = 0. @code{rIi <- rIi - M}.
+@end ftable
+
+In the above instructions, the subfield @samp{ADDRESS} acts as an
+immediate (indexed) operand, and allow us to set directly the contents
+of the MIX registers without an indirection to the memory cells (in a
+real CPU this would mean that they are faster that the previously
+discussed instructions, whose operands are fetched from memory). So, if
+you want to store in @samp{rA} the value -2000 (- 00 00 00 31 16), you
+can use the binary instruction @w{+ 31 16 00 03 48}, or, symbolically,
+
+@example
+ENNA 2000
+@end example
+@noindent
+Used in conjuction with the store operations (@samp{STA}, @samp{STX},
+etc.), these instructions also allow you to set memory cells contents to
+concrete values.
+
+Note that in these address transfer operators, the @samp{MOD} field is
+not a subfield specificator, but serves to define (together with
+@samp{OPCODE}) the concrete operation to be performed.
+
+@node Comparison operators, Jump operators, Address transfer operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Comparison operators
+@cindex comparison operators
+
+So far, we have learned how to move values around between the MIX
+registers and its memory cells, and also how to perform arithmetic
+operations using these values. But, in order to write non-trivial
+programs, other functionalities are needed. One of the most common is
+the ability to compare two values, which, combined with jumps, will
+allow the execution of conditional statements.
+The following instructions compare the value of a register with @samp{V}, and
+set the @sc{cm} indicator to the result of the comparison (i.e. to
+@samp{E}, @samp{G} or @samp{L}, equal, greater or lesser respectively).
+
+@ftable @code
+@item CMPA
+Compare [rA] with V. OPCODE = 56, MOD = fspec.
+@item CMPX
+Compare [rX] with V. OPCODE = 63, MOD = fspec.
+@item CMPi
+Compare [rIi] with V. OPCODE = 56 + i, MOD = fspec.
+@end ftable
+
+As explained above, these instructions modify the value of the MIX
+comparison indicator; but maybe you are asking yourself how do you use
+this value: enter jump operators, in the next subsection.
+
+@node Jump operators, Input-output operators, Comparison operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Jump operators
+@cindex jump operators
+
+The MIX computer has an internal register, called the @dfn{location
+counter}, which stores the address of the next instruction to be fetched
+and executed by the virtual CPU. You cannot directly modify the contents
+of this internal register with a load instruction: after fetching the
+current instruction from memory, it is automatically increased in one
+unit by the MIX. However, there is a set of instructions (which we call
+jump instructions) which can alter the contents of the location counter
+provided some condition is met. When this occurs, the value of the next
+instruction address that would have been fetched in the absence of the
+jump is stored in @samp{rJ} (except for @code{JSJ}), and the location
+counter is set to the value of @samp{M} (so that the next instruction is
+fetched from this new address). Later on, you can return to the point
+when the jump occurred reading the address stored in @samp{rJ}.
+
+The MIX computer provides the following jump instructions:
+With these instructions you force a jump to the specified address. Use
+@samp{JSJ} if you do not care about the return address.
+
+@ftable @code
+@item JMP
+Unconditional jump. OPCODE = 39, MOD = 0.
+@item JSJ
+Unconditional jump, but rJ is not modified. OPCODE = 39, MOD = 1.
+@end ftable
+
+These instructions check the overflow toggle to decide whether to jump
+or not.
+
+@ftable @code
+@item JOV
+Jump if OV is set (and turn it off). OPCODE = 39, MOD = 2.
+@item JNOV
+Jump if OV is not set (and turn it off). OPCODE = 39, MOD = 3.
+@end ftable
+
+In the following instructions, the jump is conditioned to the contents of the
+comparison flag:
+
+@ftable @code
+@item JL
+Jump if @w{@code{[CM] = L}}. OPCODE = 39, MOD = 4.
+@itemx JE
+Jump if @w{@code{[CM] = E}}. OPCODE = 39, MOD = 5.
+@itemx JG
+Jump if @w{@code{[CM] = G}}. OPCODE = 39, MOD = 6.
+@itemx JGE
+Jump if @code{[CM]} does not equal @code{L}. OPCODE = 39, MOD = 7.
+@itemx JNE
+Jump if @code{[CM]} does not equal @code{E}. OPCODE = 39, MOD = 8.
+@itemx JLE
+Jump if @code{[CM]} does not equal @code{G}. OPCODE = 39, MOD = 9.
+@end ftable
+
+You can also jump conditioned to the value stored in the MIX registers,
+using the following instructions:
+
+@ftable @code
+@item JAN
+@itemx JAZ
+@itemx JAP
+@itemx JANN
+@itemx JANZ
+@itemx JANP
+Jump if the content of rA is, respectively, negative, zero, positive,
+non-negative, non-zero or non-positive.
+OPCODE = 40, MOD = 0, 1, 2, 3, 4, 5.
+@item JXN
+@itemx JXZ
+@itemx JXP
+@itemx JXNN
+@itemx JXNZ
+@itemx JXNP
+Jump if the content of rX is, respectively, negative, zero, positive,
+non-negative, non-zero or non-positive.
+OPCODE = 47, MOD = 0, 1, 2, 3, 4, 5.
+@item JiN
+@itemx JiZ
+@itemx JiP
+@itemx JiNN
+@itemx JiNZ
+@itemx JiNP
+Jump if the content of rIi is, respectively, negative, zero, positive,
+non-negative, non-zero or non-positive.
+OPCODE = 40 + i, MOD = 0, 1, 2, 3, 4, 5.
+@end ftable
+
+
+@node Input-output operators, Conversion operators, Jump operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Input-output operators
+@cindex input-output operators
+
+As explained in previous sections (@pxref{MIX architecture}), the MIX
+computer can interact with a series of block devices. To that end, you
+have at your disposal the following instructions:
+
+@ftable @code
+@item IN
+Transfer a block of words from the specified unit to memory, starting at
+address M.
+OPCODE = 36, MOD = I/O unit.
+@item OUT
+Transfer a block of words from memory (starting at address M) to the
+specified unit.
+OPCODE = 37, MOD = I/O unit.
+@item IOC
+Perfom a control operation (given by M) on the specified unit.
+OPCODE = 35, MOD = I/O unit.
+@item JRED
+Jump to M if the specified unit is ready.
+OPCODE = 38, MOD = I/O unit.
+@item JBUS
+Jump to M if the specified unit is busy.
+OPCODE = 34, MOD = I/O unit.
+@end ftable
+@noindent
+In all the above instructions, the @samp{MOD} subfile must be in the
+range 0-20, since it denotes the operation's target device. The
+@samp{IOC} instruction only makes sense for tape devices (@samp{MOD} =
+0-7 or 20): it shifts the read/write pointer by the number of words
+given by @samp{M} (if it equals zero, the tape is rewound)@footnote{In
+Knuth's original definition, there are other control operations
+available, but they do not make sense when implementing the block
+devices as disk files (as we do in @sc{mdk} simulator). For the same
+reason, @sc{mdk} devices are always ready, since all input-output
+operations are performed using synchronous system calls.}.
+
+
+@node Conversion operators, Shift operators, Input-output operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Conversion operators
+@cindex conversion operators
+
+The following instructions convert between numerical values and their
+character representations.
+
+@ftable @code
+@item NUM
+Convert rAX, assumed to contain a character representation of a number,
+to its numerical value and store it in rA.
+OPCODE = 5, MOD = 0.
+@item CHAR
+Convert the number stored in rA to a character representation and store
+it in rAX.
+OPCODE = 5, MOD = 1.
+@end ftable
+@noindent
+Digits are represented in MIX by the range of values 30-39 (digits
+0-9). Thus, if the contents of @samp{rA} and @samp{rX} are, for instance,
+
+@example
+[rA] = + 30 30 31 32 33
+[rX] = + 31 35 39 30 34
+@end example
+@noindent
+the represented number is 0012315904, and @samp{NUM} will store this
+value in @samp{rA} (i.e., we end up with @samp{[rA]} = @w{+ 0 46 62 52
+0} = 12315904).
+
+If any byte in @samp{rA} or @samp{rB} does not belong to the range
+30-39, it is interpreted by @samp{NUM} as the digit obtained by taking
+its value modulo 10. E.g. values 0, 10, 20, 30, 40, 50, 60 all represent the
+digit 0; 2, 12, 22, etc. represent the digit 2, and so on. For
+instance, the number 0012315904 mentioned above could also be
+represented as
+
+@example
+[rA] = + 10 40 31 52 23
+[rX] = + 11 35 49 20 54
+@end example
+
+@samp{CHAR} performs the inverse operation, using only the values 30
+to 39 for representing digits 0-9.
+
+@node Shift operators, Miscellaneous operators, Conversion operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Shift operators
+@cindex shift
+@cindex shift operators
+
+The following instructions perform byte-wise shifts of the contents of
+@samp{rA} and @samp{rX}.
+
+@ftable @code
+@item SLA
+@itemx SRA
+@itemx SLAX
+@itemx SRAX
+@itemx SLC
+@itemx SRC
+Shift rA or rAX left, right, or rAX circularly (see example below)
+left or right. M specifies the number of bytes to be shifted.
+OPCODE = 6, MOD = 0, 1, 2, 3, 4, 5.
+@end ftable
+@noindent
+If we begin with, say, @samp{[rA]} = @w{- 01 02 03 04 05}, we would
+have the following modifications to @samp{rA} contents when performing
+the instructions on the left column:
+
+@multitable {SLA 00} {[rA] = - 00 00 00 00 00}
+@item SLA 2 @tab [rA] = - 03 04 05 00 00
+@item SLA 6 @tab [rA] = - 00 00 00 00 00
+@item SRA 1 @tab [rA] = - 00 01 02 03 04
+@end multitable
+@noindent
+Note that the sign is unaffected by shift operations. On the other
+hand, @samp{SLC}, @samp{SRC}, @samp{SLAX} and @samp{SRAX} treat
+@samp{rA} and @samp{rX} as a single 10-bytes register (ignoring again
+the signs). For instance, if we begin with @samp{[rA]} = @w{+ 01 02 03
+04 05} and @samp{[rX]} = @w{- 06 07 08 09 10}, we would have:
+
+@multitable {SLC 00} {[rA] = - 00 00 00 00 00} {[rA] = - 00 00 00 00 00}
+@item SLC 3 @tab [rA] =  + 04 05 06 07 08 @tab [rX] = - 09 10 01 02 03
+@item SLAX 3 @tab [rA] = + 04 05 06 07 08 @tab [rX] = - 09 10 00 00 00
+@item SRC 4 @tab [rA] =  + 07 08 09 10 01 @tab [rX] = - 02 03 04 05 06
+@item SRAX 4 @tab [rA] =  + 00 00 00 00 01 @tab [rX] = - 02 03 04 05 06
+@end multitable
+
+@node Miscellaneous operators, Execution times, Shift operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Miscellaneous operators
+@cindex miscellaneous operators
+
+Finally, we list in the following table three miscellaneous MIX
+instructions which do not fit in any of the previous subsections:
+
+@ftable @code
+@item MOVE
+Move MOD words from M to the location stored in rI1.
+OPCODE = 7, MOD = no. of words.
+@item NOP
+No operation. OPCODE = 0, MOD = 0.
+@item HLT
+Halt. Stops instruction fetching. OPCODE = 5, MOD = 2.
+@end ftable
+@noindent
+The only effect of executing @samp{NOP} is increasing the location
+counter, while @samp{HLT} usually marks program termination.
+
+@node Execution times,  , Miscellaneous operators, MIX instruction set
+@comment  node-name,  next,  previous,  up
+@subsubsection Execution times
+
+@cindex exection time
+@cindex time
+
+When writing MIXAL programs (or any kind of programs, for that
+matter), whe shall often be interested in their execution
+time. Loosely speaking, we will interested in the answer to the
+question: how long takes a program to execute? Of course, this
+execution time will be a function of the input size, and the answer to
+our question is commonly given as the asymptotic behaviour as a
+function of the input size. At any rate, to compute this asymptotic
+behaviour, we need a measure of how long execution of a single
+instruction takes in our (virtual) CPU. Therefore, each MIX
+instruction will have an associated execution time, given in arbitrary
+units (in a real computer, the value of this unit will depend on the
+hardware configuration). When our MIX virtual machine executes
+programs, it will (optionally) give you the value of their execution
+time based upon the execution time of each single instruction.
+
+In the following table, the execution times (in the above mentioned
+arbitrary units) of the MIX instructions are given.
+
+@multitable {INSSSS} {01} {INSSSS} {01} {INSSSS} {01} {INSSSS} {01}
+@item @code{NOP} @tab 1 @tab @code{ADD} @tab 2 @tab @code{SUB}
+@tab 2 @tab @code{MUL} @tab 10
+@item @code{DIV} @tab 12 @tab @code{NUM} @tab 10 @tab @code{CHAR}
+@tab 10 @tab @code{HLT} @tab 10
+@item @code{SLx} @tab 2 @tab @code{SRx} @tab 2 @tab @code{LDx}
+@tab  2 @tab @code{STx} @tab 2
+@item @code{JBUS} @tab 1 @tab @code{IOC} @tab 1 @tab @code{IN}
+@tab  1@tab @code{OUT} @tab 1
+@item @code{JRED} @tab 1 @tab @code{Jx} @tab 1 @tab @code{INCx}
+@tab  1 @tab @code{DECx} @tab 1
+@item @code{ENTx} @tab 1 @tab @code{ENNx} @tab 1 @tab @code{CMPx}
+@tab  1 @tab @code{MOVE} @tab 1+2F
+@end multitable
+
+In the above table, 'F' stands for the number of blocks to be moved
+(given by the @code{FSPEC} subfield of the instruction); @code{SLx} and
+@code{SRx} are a short cut for the byte-shifting operations; @code{LDx}
+denote all the loading operations; @code{STx} are the storing
+operations; @code{Jx} stands for all the jump operations, and so on with
+the rest of abbreviations.
+
+@node MIXAL,  , The MIX computer, MIX and MIXAL tutorial
+@comment  node-name,  next,  previous,  up
+@section MIXAL
+@cindex MIXAL
+@cindex MIX assembly language
+@cindex assembly
+
+In the previous sections we have listed all the available MIX binary
+instructions. As we have shown, each instruction is represented by a
+word which is fetched from memory and executed by the MIX virtual
+CPU. As is the case with real computers, the MIX knows how to decode
+instructions in binary format (the so--called machine language), but a
+human programmer would have a tough time if she were to write her
+programs in machine language. Fortunately, the MIX computer can be
+programmed using an assembly language, MIXAL, which provides a symbolic
+way of writing the binary instructions understood by the imaginary MIX
+computer. If you have used assembler languages before, you will find
+MIXAL a very familiar language. MIXAL source files are translated
+to machine language by a MIX assembler, which produces a binary file (the
+actual MIX program) which can be directly loaded into the MIX memory and
+subsequently executed.
+
+In this section, we describe MIXAL, the MIX assembly language. The
+implementation of the MIX assembler program and MIX computer simulator
+provided by @sc{mdk} are described later on (@pxref{Getting started}).
+
+@menu
+* Basic structure::             Writing basic MIXAL programs.
+* MIXAL directives::            Assembler directives.
+* Expressions::                 Evaluation of expressions.
+* W-expressions::               Evaluation of w-expressions.
+* Local symbols::               Special symbol table entries.
+* Literal constants::           Specifying an immediate operand.
+@end menu
+
+@node Basic structure, MIXAL directives, MIXAL, MIXAL
+@comment  node-name,  next,  previous,  up
+@subsection Basic program structure
+
+The MIX assembler reads MIXAL files line by line, producing, when
+required, a binary instruction, which is associated to a predefined
+memory address. To keep track of the current address, the assembler
+maintains an internal location counter which is incremented each time an
+instruction is compiled. In addition to MIX instructions, you can
+include in MIXAL file assembly directives (or pseudoinstructions)
+addressed at the assembler itself (for instance, telling it where the
+program starts and ends, or to reposition the location counter; see below).
+
+MIX instructions and assembler directives@footnote{We shall call them,
+collectively, MIXAL instructions.} are written in MIXAL (one per
+source file line) according to the following pattern:
+
+@example
+[LABEL]   MNEMONIC  [OPERAND]   [COMMENT]
+@end example
+
+@noindent
+where @samp{OPERAND} is of the form
+
+@example
+[ADDRESS][,INDEX][(MOD)]
+@end example
+
+Items between square brackets are optional, and
+
+@table @code
+@item LABEL
+is an alphanumeric identifier (a @dfn{symbol}) which gets the current
+value of the location counter, and can be used in subsequent
+expressions,
+@item MNEMONIC
+is a literal denoting the operation code of the instruction
+(e.g. @code{LDA}, @code{STA}; see @pxref{MIX instruction set}) or an
+assembly pseudoinstruction (e.g. @code{ORG}, @code{EQU}),
+@item ADDRESS
+is an expression evaluating to the address subfield of the instruction,
+@item INDEX
+is an expression evaluating to the index subfield of the instruction, which
+defaults to 0 (i.e., no use of indexing) and can only be used when
+@code{ADDRESS} is present,
+@item MOD
+is an expression evaluating to the mod subfield of the instruction. Its
+default value, when omitted, depends on @code{OPCODE},
+@item COMMENT
+any number of spaces after the operand mark the beggining of a comment,
+i.e. any text separated by white space from the operand is ignored by
+the assembler (note that spaces are not allowed within the
+@samp{OPERAND} field).
+@end table
+
+Note that spaces are @emph{not} allowed between the @code{ADDRESS},
+@code{INDEX} and @code{MOD} fields if they are present. White space is
+used to separate the label, operation code and operand parts of the
+instruction@footnote{In fact, Knuth's definition of MIXAL restricts the
+column number at which each of these instruction parts must start. The
+MIXAL assembler included in @sc{mdk}, @code{mixasm}, does not impose
+such restriction.}.
+
+We have already listed the mnemonics associated will each MIX
+instructions; sample MIXAL instructions representing MIX instructions
+are:
+@example
+HERE     LDA  2000         HERE represents the current location counter
+         LDX  HERE,2(1:3)  this is a comment
+         JMP  1234
+@end example
+
+@node MIXAL directives, Expressions, Basic structure, MIXAL
+@comment  node-name,  next,  previous,  up
+@subsection MIXAL directives
+
+MIXAL instructions can be either one of the MIX machine instructions
+(@pxref{MIX instruction set}) or one of the following assembly
+pseudoinstructions:
+
+@ftable @code
+@item ORIG
+Sets the value of the memory address to which following instructions
+will be allocated after compilation.
+@item EQU
+Used to define a symbol's value, e.g. @w{@code{SYM  EQU  2*200/3}}.
+@item CON
+The value of the given expression is copied directly into the current
+memory address.
+@item ALF
+Takes as operand five characters, constituting the five bytes of a word
+which is copied directly into the current memory address.
+@item END
+Marks the end of the program. Its operand gives the start address for
+program execution.
+@end ftable
+
+The operand of @code{ORIG}, @code{EQU}, @code{CON} and @code{END} can be
+any expression evaluating to a constant MIX word, i.e., either a simple
+MIXAL expression (composed of numbers, symbols and binary operators,
+@pxref{Expressions}) or a w-expression (@pxref{W-expressions}).
+
+All MIXAL programs must contain an @code{END} directive, with a twofold
+end: first, it marks the end of the assembler job, and, in the second
+place, its (mandatory) operand indicates the start address for the
+compiled program (that is, the address at which the virtual MIX machine
+must begin fetching instructions after loading the program). It is also
+very common (although not mandatory) to include at least an @code{ORIG}
+directive to mark the initial value of the assembler's location counter
+(remember that it stores the address associated with each compiled MIX
+instruction). Thus, a minimal MIXAL program would be
+
+@example
+          ORIG  2000    set the initial compilation adress
+          NOP           this instruction will be loaded at adress 2000
+          HLT           and this one at address 2001
+          END   2000    end of program; start at address 2000
+this line is not parsed by the assembler
+@end example
+@noindent
+The assembler will generate two binary instructions (@code{NOP} (@w{+ 00
+00 00 00 00}) and @code{HLT} (+ 00 00 02 05)), which will be loaded at
+addresses 2000 and 2001. Execution of the program will begin at address
+2000. Every MIXAL program should also include a @code{HLT} instruction,
+which will mark the end of program execution (but not of program
+compilation).
+
+The @code{EQU} directive allows the definition of symbolic names for
+specific values. For instance, we could rewrite the above program as
+follows:
+
+@example
+START     EQU   2000
+          ORIG  START
+          NOP
+          HLT
+          END   START
+@end example
+@noindent
+which would give rise to the same compiled code. Symbolic constants (or
+symbols, for short) can also be implicitly defined placing them in the
+@code{LABEL} field of a MIXAL instruction: in this case, the assembler
+assigns to the symbol the value of the location counter before compiling
+the line. Hence, a third way of writing our trivial program is
+
+@example
+          ORIG  2000
+START     NOP
+          HLT
+          END   START
+@end example
+
+The @code{CON} directive allows you to directly specify the contents of
+the memory address pointed by the location counter. For instance, when
+the assembler encounters the following code snippet
+
+@example
+          ORIG  1150
+          CON   -1823473
+@end example
+@noindent
+it will assign to the memory cell number 1150 the contents @w{- 00 06 61
+11 49} (which corresponds to the decimal value -1823473).
+
+Finally, the @code{ALF} directive let's you specify the memory contents
+as a set of five (optionally quoted) characters, which are translated by
+the assembler to their byte values, conforming in that way the binary
+word that is to be stored in the corresponding memory cell. This
+directive comes in handy when you need to store printable messages in a
+memory address, as in the following example @footnote{In the original
+MIXAL definition, the @code{ALF} argument is not quoted. You can write
+the operand (as the @code{ADDRESS} field) without quotes, but, in this
+case, you must follow the alignment rules of the original MIXAL
+definition (namely, the @code{ADDRESS} must start at column 17).}:
+
+@example
+          OUT  MSG       MSG is not yet defined here (future reference)
+MSG       ALF  "THIS "   MSG gets defined here
+          ALF  "IS A "
+          ALF  "MESSA"
+          ALF  "GE.  "
+@end example
+@noindent
+The above snippet also shows the use of a @dfn{future reference}, that
+is, the usage of a symbol (@code{MSG} in the example) prior of its actual
+definition. The MIXAL assembler is able to handle future references
+subject to some limitations which are described in the following section
+(@pxref{Expressions}).
+
+@cindex comments
+
+Any line starting with an asterisk is treated as a comment and ignored
+by the assembler.
+
+@example
+* This is a comment: this line is ignored.
+    * This line is an error: * must be in column 1.
+@end example
+
+As noted in the previous section, comments can also be located after the
+@code{OPERAND} field of an instruction, separated from it by white
+space, as in
+
+@example
+LABEL     LDA   100  This is also a comment
+@end example
+
+@node Expressions, W-expressions, MIXAL directives, MIXAL
+@comment  node-name,  next,  previous,  up
+@subsection Expressions
+@cindex operator
+@cindex binary operator
+@cindex unary operator
+The @code{ADDRESS}, @code{INDEX} and @code{MOD} fields of a MIXAL
+instruction can be expressions, formed by numbers, identifiers and
+binary operators (@code{+ - * / // :}). @code{+} and @code{-} can also
+be used as unary operators. Operator precedence is from left to right:
+there is no other operator precedence rule, and parentheses cannot be
+used for grouping. A stand-alone asterisk denotes the current memory
+location; thus, for instance,
+
+@example
+     4+2**
+@end example
+
+@noindent
+evaluates to 6 (4 plus 2) times the current memory location. White space
+is not allowed within expressions.
+
+The special binary operator @code{:} has the same meaning as in fspecs,
+i.e.,
+
+@example
+A:B = 8*A + B
+@end example
+@noindent
+while @code{A//B} stands for the quotient of the ten-byte number @w{@code{A} 00
+00 00 00 00} (that is, A right-padded with 5 null bytes or, what amounts
+to the same, multiplied by 64 to the fifth power) divided by
+@code{B}. Sample expressions are:
+
+@example
+18-8*3 = 30
+14/3 = 4
+1+3:11 = 4:11 = 43
+1//64 = (01 00 00 00 00 00)/(00 00 00 01 00) = (01 00 00 00 00)
+@end example
+@noindent
+Note that all MIXAL expressions evaluate to a MIX word (by definition).
+
+All symbols appearing within an expression must be previously defined. Future
+references are only allowed when appearing standalone (or modified by
+an unary operator) in the @code{ADDRESS} part of a MIXAL instruction,
+e.g.
+
+@example
+* OK: stand alone future reference
+         STA  -S1(1:5)
+* ERROR: future reference in expression
+         LDX  2-S1
+S1       LD1  2000
+@end example
+
+@node W-expressions, Local symbols, Expressions, MIXAL
+@comment  node-name,  next,  previous,  up
+@subsection W-expressions
+@cindex w-expressions
+
+Besides expressions, as described above (@pxref{Expressions}), the MIXAL
+assembler is able to handle the so called @dfn{w-expressions} as the
+operands of the directives @code{ORIG}, @code{EQU}, @code{CON} and
+@code{END} (@pxref{MIXAL directives}). The general form of a
+w-expression is the following:
+
+@example
+     WEXP = EXP[(EXP)][,WEXP]
+@end example
+@noindent
+where @code{EXP} stands for an expression and square brackets denote
+optional items. Thus, a w-expression is made by an expression, followed
+by an optional expression between parenthesis, followed by any number
+of similar constructs separated by commas. Sample w-expressions are:
+
+@example
+2000
+235(3)
+S1+3(S2),3000
+S1,S2(3:5),23
+@end example
+
+W-expressions are evaluated from left to right as follows:
+
+@itemize
+@item
+Start with an accumulated result @samp{w} equal to 0.
+@item
+Take the first expression of the comma-separated list and evaluate
+it. For instance, if the w-expression is @samp{S1+2(2:4),2000(S2)}, we
+evaluate first @samp{S1+2}; let's suppose that @samp{S1} equals
+265230: then @samp{S1+2 = 265232 = + 00 01 00 48 16}.
+@item
+Evaluate the expression within parenthesis, reducing it to an f-spec
+of the form @samp{L:R}. In our previous example, the expression
+between parenthesis already has the desired form: 2:4.
+@item
+Substitute the bytes of the accumulated result @samp{w} designated by
+the f-spec using those of the previous expression value. In our sample,
+@samp{w = + 00 00 00 00 00}, and we must substitute bytes 2, 3 and 4 of
+@samp{w} using values from 265232. We need 3 bytes, and we take the
+least significant ones: 00, 48, and 16, and insert them in positions
+2, 3 and 4 of @samp{w}, obtaining @samp{w = + 00 00 48 16 00}.
+@item
+Repeat this operation with the remaining terms, acting on the new
+value of @samp{w}. In our example, if, say, @samp{S2 = 1:1}, we must
+substitute the first byte of @samp{w} using one byte (the least
+significant) from 2000, that is, 16 (since 2000 = + 00 00 00 31 16)
+and, therefore, we obtain @samp{w = + 16 00 48 16 00}; summing up, we
+have obtained @samp{265232(1:4),2000(1:1) = + 16 00 48 16 00 =
+268633088}.
+@end itemize
+
+As a second example, in the w-expression
+@example
+1(1:2),66(4:5)
+@end example
+@noindent
+we first take two bytes from 1 (00 and 01) and store them as bytes 1 and
+2 of the result (obtaining @w{@samp{+ 00 01 00 00 00}}) and, afterwards,
+take two bytes from 66 (01 and 02) and store them as bytes 4 and 5 of
+the result, obtaining @w{@samp{+ 00 01 00 01 02}} (262210). The process
+is repeated for each new comma-separated example. For instance:
+
+@example
+1(1:1),2(2:2),3(3:3),4(4:4) = 01 02 03 04 00
+@end example
+
+As stated before, w-expressions can only appear as the operands of MIXAL
+directives taking a constant value (@code{ORIG}, @code{EQU}, @code{CON}
+and @code{END}). Future references are @emph{not} allowed within
+w-expressions (i.e., all symbols appearing in a w-expression must be
+defined before it is used).
+
+@node Local symbols, Literal constants, W-expressions, MIXAL
+@comment  node-name,  next,  previous,  up
+@subsection Local symbols
+@cindex local symbols
+
+Besides user defined symbols, MIXAL programmers can use the so called
+@dfn{local symbols}, which are symbols of the form @code{[1-9][HBF]}. A
+local symbol @code{nB} refers to the address of the last previous
+occurrence of @code{nH} as a label, while @code{nF} refers to the next
+@code{nH} occurrence. Unlike user defined symbols, @code{nH} can appear
+multiple times in the @code{LABEL} part of different MIXAL
+instructions. The following code shows an instance of local symbols'
+usage:
+
+@example
+* line 1
+1H    LDA  100
+* line 2: 1B refers to address of line 1, 3F refers to address of line 4
+      STA  3F,2(1B//2)
+* line 3: redefinition of 1H
+1H    STZ
+* line 4: 1B refers to address of line 3
+3H    JMP  1B
+@end example
+
+Note that a @code{B} local symbol never refers to a definition in its
+own line, that is, in the following program:
+
+@example
+		ORIG 1999
+ST		NOP
+3H		EQU 69
+3H		ENTA 3B  local symbol 3B refers to 3H in previous line
+		HLT
+		END ST
+@end example
+@noindent
+the contents of @samp{rA} is set to 69 and @emph{not} to 2001. An
+specially tricky case occurs when using local symbols in conjunction
+with @code{ORIG} pseudoinstructions. To wit@footnote{The author wants to
+thank Philip E. King for pointing these two special cases of local
+symbol usage to him.},
+
+@example
+		ORIG 1999
+ST		NOP
+3H		CON 10
+		ENT1 *
+		LDA 3B
+** rI1 is 2001, rA is 10.  So far so good!
+3H		ORIG 3B+1000
+** at this point 3H equals 2003
+** and the location counter equals 3000.
+		ENT2 *
+		LDX 3B
+** rI2 contains 3000, rX contains 2003.
+		HLT
+		END ST
+@end example
+
+@node Literal constants,  , Local symbols, MIXAL
+@comment  node-name,  next,  previous,  up
+@subsection Literal constants
+@cindex literal constants
+
+MIXAL allows the introduction of @dfn{literal constants}, which are
+automatically stored in memory addresses after the end of the program by
+the assembler. Literal constants are denoted as @code{=wexp=}, where
+@code{wexp} is a w-expression (@pxref{W-expressions}). For instance, the
+code
+
+@example
+L         EQU   5
+          LDA   =20-L=
+@end example
+
+causes the assembler to add after the program's end an instruction
+with contents 15 (@samp{20-L}), and to assemble the above code as the
+instruction @w{@code{ LDA a}}, where @code{a} stands for the address
+in which the value 15 is stored. In other words, the compiled code is
+equivalent to the following:
+
+@example
+L         EQU  5
+          LDA  a
+@dots{}
+a         CON  20-L
+          END  start
+@end example
+