450(C)                          19 June 1992                          450(C)


 Name

    450 - handle special functions of the DASI 450 terminal

 Syntax

    450 [ -f ]

 Description

    The 450 command supports special functions of, and optimizes the use of,
    the DASI 450 terminal, or any terminal that is functionally identical,
    such as the Diablo 1620 or Xerox 1700.  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 sym-
    bols in the same manner as 300(C).

    The -f option sets up fast (1200 baud) output using the ETX/ACK protocol.
    The following errors are possible when using -f:

    1.  Standard output is not a terminal.

    2.  Error when opening output terminal for read.

    3.  Output terminal did not respond to ETX.

    4.  Output terminal did not respond with ACK.

    It should be noted that, unless your system contains text processing
    software, certain commands (for example, eqn, nroff, tbl, etc.) will not
    work. Use 450 to print equations neatly, in the sequence:

       neqn file ... | nroff | 450


    WARNING:  Make sure that the PLOT switch on your terminal is ON before
    450 is used.  The SPACING switch should be put in the desired position
    (either 10- or 12-pitch).  In either case, vertical spacing is 6
    lines/inch, unless dynamically changed to 8 lines per inch by an
    appropriate escape sequence.

    Use 450 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 use of 450 can be eliminated in favor of
    one of the following:

       nroff -T450 files ...

    or

       nroff -T450-12 files ...

    The use of 450 can thus often be avoided unless special delays or options
    are required; in a few cases, however, the additional movement optimiza-
    tion of 450 may produce better aligned output.

 See also

    graph(ADM), tplot(ADM), 300(C), mesg(C), stty(C), tabs(C),

 Notes

    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.