va.4

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 4 代码 · 共 123 行

.\" SCCSID: @(#)va.4	8.1	9/11/90
.\" SCCSID: @(#)va.4	8.1	9/11/90
.TH va 4 VAX "" Unsupported
.SH Name
va \- Benson-Varian interface
.SH Syntax
.B "controller va0 at uba0 csr 0164000 vector vaintr"
.br
.B "disk vz0 at va0 drive 0"
.SH Description
.NT
The configuration description, while counter-intuitive,
is actually as shown above.
.NE
.PP
The Benson-Varian printer/plotter in normally used with the programs
.MS vpr 1 ,
.MS vprint 1
or
.MS vtroff 1 .
This description is designed for those who wish to drive the Benson-Varian
directly.
.PP
In print mode, the Benson-Varian uses a modified ASCII character 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.
.PP
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.
.PP
.B 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.
.PP
To use the Benson-Varian yourself,
you must realize that you cannot open the device,
.I /dev/va0
if there is a daemon active.
You can see if there is an active daemon by doing a
.IR lpq (1)
and seeing if there are any files being printed.
.PP
To set the Benson-Varian into plot mode include the file
.RI < sys/vcmd.h >
and use the following
.IR ioctl (2)
call
.IP
ioctl(fileno(va), VSETSTATE, plotmd);
.PP
where
.I plotmd
is defined to be
.IP
\fBint\fR plotmd[] = { VPLOT, 0, 0 };
.PP
and
.I va
is the result of a call to
.I fopen
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
.PP
'nf
	\fBint\fR prtmd[] = { VPRINT, 0, 0 };
	\&...
	fflush(va);
	ioctl(fileno(va), VSETSTATE, prtmd);
	write(fileno(va), "\ef\e0", 2);
.fi
.PP
.BR N.B. :
If you use the standard I/O library with the Benson-Varian you
.B must
do
.IP
setbuf(vp, vpbuf);
.PP
where
.I vpbuf
is declared
.IP
\fBchar\fR vpbuf[BUFSIZ];
.PP
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
.B extremely
slowly and tend to grind the system to a halt.
.SH Diagnostics
The following error numbers are significant at the
time the device is opened.
.TP 10
[ENXIO]
The device is already in use.
.TP
[EIO]
The device is offline.
.PP
The following message may be printed on the console.
.PP
\fBva%d: npr timeout\fR.
.br
The device was not able to get data from
the UNIBUS within the timeout period, most likely because some other
device was hogging the bus. 
.SH Files
.PN /dev/va0
.SH See Also
lpr(1),
vtroff(1),
vp(4),
vfont(5),
lpd(8)