SysIII/usr/src/man/man1/300.1

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.TH 300 1
.SH NAME
300, 300s \- handle special functions of \s-1DASI\s+1 300 and 300s terminals
.SH SYNOPSIS
.B 300
[
.B +12
] [
.B \-n
] [
.BR \-d t,l,c
]
.PP
.B 300s
[
.B +12
] [
.B \-n
] [
.BR \-d t,l,c
]
.SH DESCRIPTION
.I 300\^
supports special functions and optimizes the use of the
.SM DASI
300
(\s-1GSI\s+1 300 or
.SM DTC
300) terminal;
.I 300s\^
performs the same functions for the
.SM DASI
300s (\s-1GSI\s+1 300s or
.SM 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%.
.I 300\^
can be used
to print equations neatly, in the sequence:
.PP
.RS
neqn file
.B \&.\|.\|.
\(bv nroff \(bv 300
.PP
.RE
.SM WARNING:
if your terminal has a
.SM PLOT
switch, make sure it is turned
.I on\^
before
.I 300\^
is used.
.PP
The behavior of
.I 300\^
can be modified by the optional flag arguments to handle
12-pitch text, fractional line spacings, messages, and delays.
.TP 9
.B +12
permits use of 12-pitch, 6 lines/inch text.
.SM 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
.SM PITCH
switch to 12, and use the
.B +12
option.
.TP 9
.BI \- 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
.I n\^
overrides the default value, thus allowing for individual taste
in the appearance of subscripts and superscripts.
For example,
.IR nroff (1)
half-lines could be made to act as quarter-lines by using
.BR \-2 .
The user could also obtain appropriate half-lines for
12-pitch, 8 lines/inch mode by using the option
.B \-3
alone,
having set the
.SM PITCH
switch to 12-pitch.
.TP 9
.BI \-d t , l , c\^
controls delay factors.
The default setting is
.BR \-d3,90,30 .
.SM 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
.I t\^
tabs,
and for every contiguous string of
.I c\^
non-blank, non-tab characters.
If a line is longer than
.I 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
.I t\^
.RI ( c )
results in two null bytes per tab (character).
The former may be needed for C programs, the latter for files like
.BR /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
.B \-d
option exists only as a last resort
for those few cases that do not otherwise print properly.
For example, the file
.B /etc/passwd
may be printed using
.BR \-d3,30,5 .
The value
.B \-d0,1
is a good one to use for C programs that have many
levels of indentation.
.IP
Note that the delay control interacts heavily
with the prevailing carriage return and
line-feed delays.
The
.IR stty (1)
modes
.B "nl0 cr2"
or
.B "nl0 cr3"
are recommended for most uses.
.PP
.I 300\^
can be used with the
.I nroff\^
.B \-s
flag or
.B \&.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.
.PP
In many (but not all) cases, the following sequences are equivalent:
.RS
.PP
nroff \-T300 files
.B \&.\|.\|.
\ \ and\ \ \ nroff files
.B \&.\|.\|.
\(bv 300
.br
nroff \-T300\-12 files
.B \&.\|.\|.
\ \ and\ \ \ nroff files
.B \&.\|.\|.
\(bv 300\ +12
.PP
.RE
The use of
.I 300\^
can thus often be avoided unless
special delays or options are required;
in a few cases, however, the additional movement optimization of
.I 300\^
may produce better-aligned output.
.PP
The
.IR neqn (1)
names of, and
resulting output for, the Greek and special characters supported
by
.I 300\^
are shown in
.IR greek (7).
.SH SEE ALSO
450(1),
eqn(1),
graph(1G),
mesg(1),
stty(1),
tabs(1),
tbl(1),
tplot(1G),
troff(1),
greek(7).
.SH BUGS
Some special characters cannot be correctly printed in column 1
because the print head cannot be moved to the left from there.
.br
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.