Re: 9825 restoration notes and questions


Paul Berger
 

Craig mentioned that error comes from the extended I/O, if the memory switch is in the 32K position when you remove the A25 card the extended I/O would not be available, this would suggest that the A25 card is participating with remapping the the ROMs.  This may indicate that the A25 is at least partially functional and the problem might be the RAM array on the card.

Paul.



On 2017-01-31 1:59 PM, Jack Rubin wrote:

Interesting - not much time to play around this morning before leaving for a few days, but I did find that with A25 in place and 64K selected, the system would note the presence/absence of the tape drive (i.e. error 43) if the Monitor Bus cable was _removed_. If the cable was in place, no error was reported whether the  tape drive was connected or not. Clearly _something_ is happening on A25 and the Monitor Bus cable is providing some signals. 

More tantalizing than conclusive. When I return home later in the week, I'll go ahead with a full physical tear-down and inspection of the other end of the Monitor Bus cable. 

More to come ...


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