HPIB [was Re: Kennedy to PC interface...]

What I would do is trace back from the data pins of the HPIB connector (IIRC that's pins 1-4 and 13-16 of the 24 pin Microribbon connector). On most modern-ish machines (anything since the 9830 :-)), there is only one chip connected to those lines, and that's the HPIN data buffer. One common type is the 75160, which comes in a 20 pin DIL package, or I guess some kind of SMD thing. But HP did make their own ASIC HPIB buffer chips -- I forget the number, but it's a 40 pin DIL thing. Anyway, if you find what chip those signals go to, post the number (even if it's an HP house number -- 1820-xxxx) and I'll see if I can identify it. There aren't that many HPIB buffer chips in common use. There's the TI set (75160/75161/75162), the HP custom one, the various Motorola ones (I forget the numbers), the Intel one (8293), and that's about it. Oh, there's the kludge way, using open-collector TTL as drivers (or before that, discrete transistors), and 7414's as receivers. -tony