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-rw-r--r--doc/mdk.texi58
1 files changed, 30 insertions, 28 deletions
diff --git a/doc/mdk.texi b/doc/mdk.texi
index d481ae4..5f7941e 100644
--- a/doc/mdk.texi
+++ b/doc/mdk.texi
@@ -283,11 +283,12 @@ significant one. The sign is denoted by index 0. Graphically,
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 @samp{(L:R)}, where
-@samp{L} denotes the first byte and @samp{R} the last byte of the
-subfield. When @samp{L} is zero, the subfield includes the word's
-sign. An fspec can also be represented as a single value @samp{F}, given
+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).
@@ -303,17 +304,17 @@ address a memory cell) and the following registers:
@cindex rIn
@cindex register
-@table @samp
-@item rA
+@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 rX
+@item @code{rX}
X register. General purpose register holding a word. Often it acts as an
extension or a replacement of @samp{rA}.
-@item rJ
+@item @code{rJ}
J (jump) register. This register stores positive two-byte values,
usually representing a jump address.
-@item rI[1-6]
+@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 is used as indexing values for the computation of
effective memory addresses.
@@ -321,7 +322,7 @@ effective memory addresses.
@cindex @sc{ov}
@cindex @sc{cm}
-@cindex @samp{Un}
+@cindex @code{un}
@cindex overflow toggle
@cindex comparison indicator
@cindex input-output devices
@@ -338,23 +339,24 @@ A @dfn{comparison indicator} (having three values: @dfn{EQUAL},
@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 @samp{Un}, where
-@samp{n} runs from 0 to 20. In Knuth's definition, @samp{U0-7} are
-magnetic tape units, @samp{U8-15} are disks and drums, @samp{U16} is a
-card reader, @samp{U17} is a card writer, @samp{U18} is a line printer
-and, @samp{U19} is a typewriter terminal, and @samp{U20}, a paper
-tape. Our implementation maps these devices to disk files, except for
-@samp{U19}, which represents the standard output.
+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, communication of the MIX computer with the external
-world is achieved by a set of input-output devices which can be
-"connected" to it. Interchange of information is done in blocks of words
-whose length depend on the device at hand (see @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:
+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
@@ -374,8 +376,8 @@ according to the following table:
@end multitable
@noindent
The value 0 represents a whitespace. Lowercase letters (d, s, p)
-correspond to symbols non representable as ASCII characters (uppercase
-delta, sigma and gamma, respectively) and byte values 56-63 have no
+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