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VRF -- Parrallel Port (fwd)

Question asked by VRFuser on Mar 31, 1997
From:  Tim Axness
To:    Vee Reflector

I used the parallel port in a similar configuration on a previous project.
The pin-out for the parallel port is nearly the same as that on an IBM PC.  You
have to have a peripheral that asserts the BUSY line on the parallel interface
back to the workstation to make it work.  I believe that is not needed on a PC
parallel interface.  I needed an interface box anyway for the device I was
trying to control, so I accomplished the needed signaling by inverting the
STROBE line and feeding it back to the BUSY line.  (I didn't use the STROBE
line in my design otherwise.)  If you need the pin-out for the parallel port,
send me an email and I can get you a copy.  It is just the standard IBM PC
printer port.

As for VEE, I wrote a simple C program and called it from VEE.  The control
sequence is passed from VEE to the C program. Each element in the control
sequence correspond to an ASCII character.  The C program uses standard printing
commands to "print" the control sequence to the parallel port. 

Hope this helps. 

>      I'm using a HP735 series workstation with v3.21 (I know, I know, I
>      haven't got v4.0 yet) and want to use the parallel port as I/O lines.
>      Anybody got an idea as to how to get vee to control the port. I have
>      not found any reference to it in any documentation.
>      Thanks,
>      Mark Keck
>      Motorola
>      Schaumburg Il

Timothy A. Axness
Applied Physics Laboratory
Johns Hopkins University