General Category > Lisa Troubleshooting and Repair
Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
AlexTheCat123:
Finally I've got some good-ish news! The disk controller problem is still a thing, but I did get the keyboard and mouse working! I decided to desolder the COP421 from my original I/O board and move it to the new board and that fixed the keyboard and mouse problems. I guess something's wrong with my COP421 replacement board, but I'm not sure what it could be since I have verified that the contents of the EPROM are correct and I've checked that all of the connections on the adapter board are good. With the keyboard and mouse working, I'm now able to enter service mode and I checked the memory location that you specified for where version of the I/O ROM is located. It matches the 00 that is displayed in the upper right hand corner of the screen during the self-test. With this problem fixed, I guess it's just a matter of getting the floppy controller working and figuring out what's wrong with my COP421 replacement board. The COP421 issue is particularly weird because my COP replacement seems to handle soft power-on just fine, making it seem like it's executing code properly, but the keyboard, mouse, and soft power-off don't work.
Lisa2:
Let it be known that the 6507 CPU is a direct replacement for the 6504 CPU on the Lisa I/O board. The 6507 may be a little easier to find since it was used in millions of Atari video games. There is a minor difference on one or two of the pins but they are not used on the Lisa. As already was mentioned the Die is a 6502 on both the 6504 and the 6507, just with different pins brought out in the package.
HTH,
Rick
AlexTheCat123:
--- Quote ---Let it be known that the 6507 CPU is a direct replacement for the 6504 CPU on the Lisa I/O board.
--- End quote ---
That's good to know! I wish I'd realized that before I bought a 6504 from China...
AlexTheCat123:
I just got the replacement 2732 I/O board EPROMs in the mail today, but my TL866II Plus programmer won't program the chips because they require a 21V Vpp when programming, but my programmer can only go up to 18V. The weird thing is that I've programmed 2716s that also require a 21V Vpp on this programmer in the past and it has worked fine, but now I'm stuck since I can't write to these EPROMs. Hopefully I can find a solution quickly and get the code into this chip!
jamesdenton:
Can you read the ROM and compare the checksum? Wonder if that would be enough to confirm.
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