18 Oct
2006
18 Oct
'06
4:33 p.m.
If you're not dealing with very high-speed
devices, (e.g. voltmeters, etc.)
and only talking to a single device, a simple bidirectional printer port
can provide most of the functionality of GPIB/HPIB. Sometime in the
mid-80's, I released a bit of code (may still be in SIMTEL) for a DOS TSR
to drive an HP Plotter through the printer port.
If not, I appear to have a copy floating around here. I've never used it,
though.
It wasn't an original idea--I saw the printer port on the Victor 9000 used
to do the same thing. Victor would even sell you a cable for that purpose.
The printer port on the Sirius (==Vistor 9000) was a GPIB port with a
strange pinout and connector. According to the schematics, it uses a
75160 to drive the data lines and a 75161 to drive the handshake lines
(for example, pin 1, which would be the strobe line on a Centronics
printer is driven by the DAV buffer in the 75161).
The whole thing was driven in software (there's a 6522, not suprisingly,
behind it :-)). The normal device drives talk to the Centronics printer,
for which you use a striaght-through cable. This is the first I've heard
of ther being a GPIB cable (and presumably driver software), though.
Talking of the Sirius, was the user port ever used for anything. That's a
50 pin header on the mainboard carrying power and ground, light pen
input, and all the port lines of a 6522. Well, one of them is also used
as the clock for the sound system, but the rest are totally uncommitted.
And was the sound input (the little header on the mainboard) ever used?
-tony