S-100 bus termination

From: Jack Peacock <peacock_at_simconv.com>
Date: Sat Jul 25 00:59:25 1998

>I was digging through some S-100 cards and came upon a Godbout active
>terminator. Do all S-100 buses require external termination, or did
more
>have it built into the mobo? Specifically, do I need to stick this
card
>into my IMSAI?
>
It depends on what kind of motherboard you have. Typically, the
terminator was at the end opposite where the front panel or CPU card
plugged in. Early S-100 motherboards ran at only 2 Mhz (8080 CPU) or
2.5 Mhz (early Z-80) so termination wasn't quite so important. Later,
when speeds were pushed past 4Mhz the terminator became crucial to
reliability. Look at the back end of your motherboard, if you don't
see an array of resistors, about 90 or so, then put the Godbout board
in the very last slot, and your CPU card as close as possible to the
front slot, right behind the front panel.

 I used one when I went to 4Mhz on the original 22 slot IMSAI
motherboard, it does help. After the IMSAI MB wore out I switched to
Thinkertoys and Godbout (later called Compupro) motherboards, they had
the terminator built in.
         Jack Peacock
Received on Sat Jul 25 1998 - 00:59:25 BST