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Old 21st Feb 2021, 8:26 pm   #611
Join Date: May 2008
Location: Derby, UK.
Posts: 7,732
Default Re: Non-working Commodore PET 3016

Originally Posted by SiriusHardware View Post
Thanks for the detail, you obviously know your 6502 very well.
Thanks for the compliment! Sign of a mis-spent youth, probably.
Originally Posted by SiriusHardware View Post
I'm hoping in the first instance that if there is a fault on one of the buffers it will make itself more obviously known and not be as subtle as you suggest.
Yes, perhaps I was being a bit pessimistic. Mind, anything's going to look a bit disappointing after that absolute money shot of the fault on the address buffers! It will all depend on the nature of the fault. Pin 5 seems not to be pulling low enough, but will it do it with the CPU disconnected?
Originally Posted by SiriusHardware View Post
If not, we'll try as you say, but as Colin already has a couple of replacements 'on shed' it may ultimately be more straightforward to replace them to rule them in or out - they are after all the same device, possibly the same batch, same age, performing a similar function to the address buffers which weren't working very well.
Indeed; and I'm confident that replacing UE9 and UE10 will produce some improvement. Maybe even a BASIC prompt, although that's probably a little too much to hope for.
If I have seen further than others, it is because I was standing on a pile of failed experiments.
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