Info needed on some 1980s-era Intel parts

[Tony Duell]

> > If you're really curious, I have schematics for the first
> > HPIB interface -- the one that goes in the HP9830. That used no special
> > ICs at all, just TTL and discretes (I have an idea the output drivers
> > were discrete transistors).
> 
> I'm always interested in learning about new GPIB implemenations.

Go over to http://www.hpmuseum.net/ . Follow the 'documentation' link then 
search for 59405 (that's the model number of the interface). IIRC, there 
are 2 documantes for that, one is a set of unofficial hand-drawn 
schematics, the other is the operating/service manual, inclduing an 
official schematic.

It's an odd design. Basically, it can transfer bytes between the HP9830's 
I/O bus and the HPIB, with the ATN line held active if you want it. There 
is no direct way to set talker or listenr status of the interface, 
instead. it detects Talk Address and Listen Address commands on the bus. 
To make the interface a talker, it can send a byte with ATN active which 
happens to be a Talk Address command with the right address. The 
interface hardware recognises that and sets talk mode. 

-tony