V10/man/mana/300.1

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.TH 300 1
.SH NAME
300, 300s \- handle special functions of DASI 300 and 300s terminals
.SH SYNOPSIS
.B 300
[
.B +12
]
[
.B \-n
]
[
.BI \-d t,l,c
]
.PP
.B 300s
[
.B +12
]
[
.B \-n
]
[
.BI \-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
.IR 450 (1),
.IR eqn (1),
.IR graph (1G),
.IR mesg (1),
.IR stty (1),
.IR tabs (1),
.IR tbl (1),
.IR tplot (1G),
.IR troff (1),
.IR 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.