4BSD/usr/man/cat4/va.4

VA(4)               UNIX Programmer's Manual                VA(4)



NAME
     va - Benson-Varian interface

SYNOPSIS
     #include <sys/vcmd.h>

DESCRIPTION
     The Benson-Varian printer/plotter in normally used with the
     programs _v_p_r(1), _v_p_r_i_n_t(1) or _v_t_r_o_f_f(1).  This description
     is designed for those who wish to drive the Benson-Varian
     directly.

     The Benson-Varian at Berkeley uses 11" by 8" fan-fold paper.
     It will print 132 characters per line in print mode and 2112
     dots per line in plot mode.

     In print mode, the Benson-Varian uses a modified ASCII char-
     acter set.  Most control characters print various non-ASCII
     graphics such as daggers, sigmas, copyright symbols, etc.
     Only LF and FF are used as format effectors.  LF acts as a
     newline, advancing to the beginning of the next line, and FF
     advances to the top of the next page.

     In plot mode, the Benson-Varian prints one raster line at a
     time.  An entire raster line of bits (2112 bits = 264 bytes)
     is sent, and then the Benson-Varian advances to the next
     raster line.

     Note: The Benson-Varian must be sent an even number of
     bytes.  If an odd number is sent, the last byte will be
     lost.  Nulls can be used in print mode to pad to an even
     number of bytes.

     To use the Benson-Varian yourself, you must realize that you
     cannot open the device, /_d_e_v/_v_a_0 if there is a daemon
     active.  You can see if there is a daemon active by doing a
     _p_s(1), or by looking in the directory /_u_s_r/_s_p_o_o_l/_v_a_d. If
     there is a file _l_o_c_k there, then there is probably a daemon
     /_u_s_r/_l_i_b/_v_a_d running.  If not, you should remove the _l_o_c_k.

     In any case, when your program tries to open the device
     /_d_e_v/_v_a_0 you may get one of two errors.  The first of these
     ENXIO indicates that the Benson-Varian is already in use.
     Your program can then _s_l_e_e_p(2) and try again in a while, or
     give up.  The second is EIO and indicates that the Benson-
     Varian is offline.

     To set the Benson-Varian into plot mode you can use the fol-
     lowing _i_o_c_t_l(2) call

          ioctl(fileno(va), VSETSTATE, plotmd);




Printed 11/10/80                                                1






VA(4)               UNIX Programmer's Manual                VA(4)



     where plotmd is defined to be

          int plotmd[] = { VPLOT, 0, 0 };

     and _v_a is the result of a call to _f_o_p_e_n on stdio.  When you
     finish using the Benson-Varian in plot mode you should
     advance to a new page by sending it a FF after putting it
     back into print mode, i.e. by
9     int prtmd[] = { VPRINT, 0, 0 };
     ...
     fflush(va);
     ioctl(fileno(va), VSETSTATE, prtmd);
     write(fileno(va), "\f\0", 2);

     _N._B.: If you use the standard I/O library with the Benson-
     Varian you must do

          setbuf(vp, vpbuf);

     where _v_p_b_u_f is declared

          char vpbuf[BUFSIZ];

     otherwise the standard I/O library, thinking that the
     Benson-Varian is a terminal (since it is a character special
     file) will not adequately buffer the data you are sending to
     the Benson-Varian.  This will cause it to run extremely
     slowly and tends to grind the system to a halt.

FILES
     /dev/va0
     /usr/include/sys/vcmd.h

SEE ALSO
     vfont(5), vpr(1), vtroff(1), vp(4)

BUGS
     The 1's (one's) and l's (lower-case el's) in the Benson-
     Varian's standard character set look very similar; caution
     is advised.











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Printed 11/10/80                                                2