IMSAI (moving along...)

From: Richard Erlacher <edick_at_idcomm.com>
Date: Thu Jul 8 19:41:45 1999

Remember when I was bitching about the S-100 having half a dozen or more
signals, any four of which would do the job? That's only true if the FP,
the CPU, and the target memory or peripheral agree on which signals those
are. That's not always the case. Some cards seem to prefer you use one
pair of signals as the active strobes with others as qualifiers, while
others require the concurrence of all before anything happens. It may be
that the memory doesn't think it's being written, or that it doesn't believe
the data is being gated onto the bus.

You might find it illuminating to reach in with a scope probe and see how
long the write and the select strobes are at the destination, and compare
them with the source.

Dick

-----Original Message-----
From: Bill Sudbrink <bill_at_chipware.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Thursday, July 08, 1999 4:58 PM
Subject: RE: IMSAI (moving along...)


>> Do you have prints for the cpu and FP? they are a must as you can
>> literally follow the signal forward or backward to the problem.
>
>For the front panel I have drawings of the board/traces, both
>solder and component sides. For the MPU-A I have nothing.
>Interestingly, I have the MPU-B Theory of Operation and Users
>Guide.
>
>Thanks,
>Bill
Received on Thu Jul 08 1999 - 19:41:45 BST