300(1) 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
300 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. 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%. 300 can be
used to print equations neatly, in the sequence:
neqn file... | nroff | 300
WARNING: if your terminal has a PLOT switch, make sure it is
turned 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.
-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
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300(1) 300(1)
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
the prevailing carriage return and line-feed
delays. The stty(1) modes nl0 cr2 or nl0 cr3 are
recommended for most uses.
300 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.
The neqn names of, and resulting output for, the Greek and
special characters supported by 300 are shown in greek(5).
FILES
/usr/bin/300
/usr/bin/300s
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300(1) 300(1)
SEE ALSO
450(1), eqn(1), mesg(1), nroff(1), stty(1), tabs(1), tbl(1),
tplot(1G), greek(5).
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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