bitfixer
Veteran Member
Another bit of information -
Just checked all the 4016 RAM on the bad PET, to eliminate that as a variable.
Used an Apple II+ as a memory tester. All the chips tested ok..
I'm wondering if somehow the instructions the PET is fetching from ROM are getting corrupted somewhere along the way.
Seems like it might be a case for making a test EPROM. I don't have an EPROM writer, but I do have a few Atmel EPROMS which are fairly simple to write with a small microcontroller circuit. May look up 6502 opcodes and make a simple test.
Just checked all the 4016 RAM on the bad PET, to eliminate that as a variable.
Used an Apple II+ as a memory tester. All the chips tested ok..
I'm wondering if somehow the instructions the PET is fetching from ROM are getting corrupted somewhere along the way.
Seems like it might be a case for making a test EPROM. I don't have an EPROM writer, but I do have a few Atmel EPROMS which are fairly simple to write with a small microcontroller circuit. May look up 6502 opcodes and make a simple test.