S-100 bus termination

From: Allison J Parent <allisonp_at_world.std.com>
Date: Tue Jul 28 07:42:12 1998

< Originally, the Altair (S-100) bus did not define a need for termination
< any kind. It was not until things on the bus started to speed up (usin
< DMA and such) that anyone apparently thought about it.

The altair bus was never specified, nor engineered. IF it were it would
not have been built that way.

It was more like people tried to makes them work and found the crashed
often and without apparent cause. Other people found if the move the
boards from one slow to another would make a program crash. Using an
extender card crashed the system. Most all found as they added memory the
system would get more or less stable. I was one of the early ones looking
at the data lines mostly if horror with my scope. Of the handfull of
computer people in the LI, NY area at the time I was one of the few with a
scope.

< Can't hurt. I will say however, I do seem to recall seeing a board or t
< that would not run on a terminated bus, but that has been so long that
< don't evem recall what it was.

There were a few really badly designed boards that couldn't drive the bus
at all well and tended to also aggravate the noise situation.

Allison
Received on Tue Jul 28 1998 - 07:42:12 BST