300, 300s --
handle special functions of DASI 300 and 300s terminals
[ +12 ] [ -n ]
[ +12 ] [ -n ]
The 300 command supports special functions and optimizes
the use of the DASI 300 (GSI 300 or DTC 300)
terminal; 300s performs the same functions for the
DASI 300s (GSI 300s or DTC 300s) terminal.
It converts half-line forward, half-line reverse, and full-line reverse
motions to the correct vertical motions.
In the following discussion of the 300 command,
it should be noted that unless your system contains the
text processing software, references to certain commands (for example,
nroff, neqn, eqn, etc.) will not work.
It also attempts to draw Greek letters and other special symbols.
It permits convenient use of 12-pitch text.
It also reduces printing time by between 5% and 70%.
The 300 command can be used
to print equations neatly, in the sequence:
neqn file ... | nroff | 300
The behavior of 300 can be modified by the optional flag
arguments to handle 12-pitch text, fractional line spacings, messages,
The 300 command can be used with the nroff
-s flag or .rd
requests, when it is necessary to insert paper manually or change fonts
in the middle of a document.
Instead of hitting the Return key in these cases, you must use the
line-feed key to get any response.
permits use of 12-pitch, 6 lines/inch text. DASI 300 terminals
normally allow only two combinations: 10-pitch, 6 lines/inch,
or 12-pitch, 8 lines/inch. To obtain the 12-pitch, 6 lines per inch
combination, the user should turn the PITCH switch to 12,
and use the +12 option.
controls the size of half-line spacing. A half-line is, by default,
equal to 4 vertical plot increments. Because each increment equals
1/48 of an inch, a 10-pitch line-feed requires 8 increments,
while a 12-pitch line-feed needs only 6. The first digit of
n overrides the default value, thus allowing for individual
taste in the appearance of subscripts and superscripts.
For example, nroff half-lines could be made to act as
quarter-lines by using -2.
The user could also obtain appropriate half-lines for
12-pitch, 8 lines/inch mode by using the option -3
alone, having set the PITCH switch to 12-pitch.
controls delay factors. The default setting is -d3,90,30.
DASI 300 terminals sometimes produce peculiar output when faced
with very long lines, too many tab characters,
or long strings of blankless, non-identical characters.
One null (delay) character is inserted in a line for every set of
t tabs, and for every contiguous string of c
non-blank, non-tab characters.
If a line is longer than l bytes, 1+(total length)/20
nulls are inserted at the end of that line. Items can be omitted from
the end of the list, implying use of the default values. Also,
a value of zero for t (c) results in two
null bytes per tab (character).
The former may be needed for C programs, the latter for files like
Because terminal behavior varies according to the specific characters
printed and the load on a system, the user may have to experiment
with these values to get correct output.
The -d option exists only as a last resort
for those few cases that do not otherwise print properly.
For example, the file /etc/passwd may be printed using
The value -d0,1 is a good one to use for C programs
that have many levels of indentation.
Note that the delay control interacts heavily with the prevailing
carriage return and line-feed delays.
modes nl0 cr2 or nl0 cr3 are recommended for most uses.
In many (but not all) cases, the following sequences are equivalent:
nroff -T300 files ... and nroff files ... | 300
nroff -T300-12 files ... and nroff files ... | 300 +12
The use of 300 can thus often be avoided unless
special delays or options are required;
in a few cases, however, the additional movement optimization of
300 may produce better aligned output.
If your terminal has a PLOT switch, make sure it is turned
on before 300 is used.
Some special characters cannot be correctly printed in column 1
because the print head cannot be moved to the left from there.
If your output contains Greek and/or reverse line-feeds, use
a friction-feed platen instead of a forms tractor; although good
enough for drafts, the latter has a tendency to slip when reversing
direction, distorting Greek characters and misaligning the first line
of text after one or more reverse line-feeds.
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003