09-25-2023, 05:14 PM
A PC-1261 with a faulty RAM chip.
The fault appears to affect only one bit in RAM that always stays 0. This bit is associated with variable B. So assigning 77777 to variable B gives 77773 instead. I don't believe there is a way on this machine to remap RAM to work around this (some Sharp PC models have address pointers to POKE to change the location of variables and BASIC programs).
The PC-1261 has a separate PCB for RAM. I could swap that out if I can find a spare PC-1261 RAM PCB somewhere. Or I could try replacing the RAM chip, which is surface mounted.
The RAM chip is marked:
4K1
SC613256
G77
I have no idea if these RAM chips (or PC-1261 RAM PCB boards) are still obtainable. Any suggestions?
- Rob
The fault appears to affect only one bit in RAM that always stays 0. This bit is associated with variable B. So assigning 77777 to variable B gives 77773 instead. I don't believe there is a way on this machine to remap RAM to work around this (some Sharp PC models have address pointers to POKE to change the location of variables and BASIC programs).
The PC-1261 has a separate PCB for RAM. I could swap that out if I can find a spare PC-1261 RAM PCB somewhere. Or I could try replacing the RAM chip, which is surface mounted.
The RAM chip is marked:
4K1
SC613256
G77
I have no idea if these RAM chips (or PC-1261 RAM PCB boards) are still obtainable. Any suggestions?
- Rob