300(1) (Terminal Filters Utilities) 300(1)
NAME
300, 300s - handle special functions of DASI 300 and 300s
terminals
SYNOPSIS
300 [ +12 ] [ -n ] [ -dt,l,c ]
300s [ +12 ] [ -n ] [ -dt,l,c ]
DESCRIPTION
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 DOCUMENTER'S WORKBENCH Software, references to certain
commands (e.g., 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 5 to 70%. The 300 command can be
used to print equations neatly, in the sequence:
neqn file ... | nroff | 300
WARNING. Make sure the PLOT switch on your terminal is ON
before 300 is used.
The behavior of 300 can be modified by the optional flag
arguments to handle 12-pitch text, fractional line spacings,
messages, and delays.
+12 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.
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300(1) (Terminal Filters Utilities) 300(1)
-n 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.
-dt,l,c 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 /etc/passwd. 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 -d3,30,5. 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
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300(1) (Terminal Filters Utilities) 300(1)
the prevailing carriage return and line-feed
delays. The stty(1) modes nl0 cr2 or nl0 cr3 are
recommended for most uses.
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.
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.
SEE ALSO
450(1), mesg(1), stty(1), tabs(1).
BUGS
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.
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