Posted By
crock
on 2020-01-21
02:03:32
 |  Re: Plus 4 acting strangely
Hi David, the message you see means that a possible addressing issue is identified on A15. For addressing issues, the $8000 is the address line, rather than a explicit location. If you read how the addressing tests work on the Diag264 web page, it might make more sense.
If you've replaced the 257's, swap them over and see if it changes. Then swap all the DRAM's over. If the message does not change, I would suspect another broken trace or dry joint.
The other possibility is that the signals from the TED which bank out the ROM are not working. From BASIC, try POKEing values in the range above 32768 and see what you PEEK back.
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