HP-IB disc drive emulation program available

It's not hard to make a GPIB interface without using a special decoder chip. I uilt a triival HPIB-Centronics interface (to run a parallel printer from a PERQ) usign a couple og 16V8 GALs and a few TTL buffers. And it's been doneby bit-banging many times. IIRC most of the handshakers are 'interlocked' so the software can take arbitrarily long to respond to a change of state of one of the signals. There is oen (I think only one) case where the timing is critical, which may ddd a couple of gates to the design. All the Commodore GPIB disk drives, printers (and indeed PETs) bit-banged the interface. Commodore never used any of the speical controller chips AFAIK. Mind you, the Commoodore GPIB is a little 'odd' when it comes to timing (I've seen 3rd party devices designed to link to PETs that work fine for that but which won't work on amost other GPIB systems). Even HP bit-banged it sometimes. The 82169 HPIL-HPIB translator uses an 8049 and no HPIB interface chip. The other 40 pin package on the PCB is an HP buffer chip with almost no internal logic. THere are several series of thise, I have no idea which, if any, are still current parts (If I was designing something new, I'd want to use a part that was still in full production, of course) Intel made the 8298 (which I know very little about). Motorola made the 3446, 3447 and 3448. Those 3 are quad uffers with different arrangements of transmit-anable lines, etc. TI made the 75160 (octal data line buffer), 75161 (Octal control line buffer for either devices or, IIRC, controllers in a signle-controller system) and 75162 (octal control line buffer in mulitple-controller systems). I've used the Motorola and TI parts, and have data sheets. That may be the case I am thinking of. Maybe looking at a PET scheamtic would help, presumalby it can handle this provlem. The HP59401 analyser is a fun toy, but I don't want it on the bus all the time :-) -tony