S-100 bus pin assignments new and old.

[Hugo Holden]

A question has come up on a nearby thread that involves pin assignments on the S-100 bus. Coincidentally I have been looking at these lately.

As noted by Glitch after the new standard some pins were grounded on some newer boards.

I wanted to send logic signals between two boards in my SOL-20 without using a link wire, so I was looking around on the bus for some unused pins, in the Sol-20 at least.

The ones I can find appear to be labelled RFU, pin 27 and pin 28, pin 69 pin 71 and another two pins possibly pin 65 & 66 labelled as NDEF. And possibly pin 98 labelled *Error.

If I was going to hijack any of those pins for transmission of a logic signal between boards, which pins would least likely get me into trouble or which ones might be seldom if ever used by most cards ?

[DeltaDon]

Google is your friend.

But since you asked: http://retrotechnology.com/herbs_stuff/s100bus.html

Note IEEE-696 defined new use next to each listing for IMSAI/Altair usage. Several reserved pins plus 65/66 for custom use that might be used on other systems.


and also: http://www.s100computers.com/S100%20Bus%20Pins.htm

[Hugo Holden]

Google is your friend.

But since you asked: http://retrotechnology.com/herbs_stuff/s100bus.html

Note IEEE-696 defined new use next to each listing for IMSAI/Altair usage. Several reserved pins plus 65/66 for custom use that might be used on other systems.


and also: http://www.s100computers.com/S100%20Bus%20Pins.htm

I had seen the list on S-100 computers. But not the retrotechnology list. It looks like the best ones to use will be 65 & 66.

Thanks.

[DeltaDon]

Glad to help out. OBTW, I found those lists some time ago when trying to figure out why a 256K RAM board won't play nice with my otherwise operating Delta Products S-100 system. DP used a couple of non-696 pin assignments and I needed to move one of them to an unassigned pin.