I have a Apple ][ plus that I acquired that was working fine when I last used it. Keyboard correctly displayed all characters. Well, I decided to take it all apart and give it a good cleaning top to bottom. I put it back together and in the middle of doing so I mistakenly put the ribbon cable for the keyboard on backwards. Started the computer and I could not enter any characters. Took the keyboard back out and correctly connected the ribbon cable that time. Now when I type, the normal letters in the middle display fine but the enter key does not go to the next line and instead displays M's and the number keys all display other letters than what is it supposed to be. Same with punctuation. I read up on this issue and found the warning after the fact that connecting the ribbon cable incorrectly will lead to damage of the keyboard. Lesson learned. Is it really no way to repair the keyboard back to working order or am I going to be looking for a replacement on eBay? Thanks!
Anonymous
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If the decoder chip on the board is MC8748... then you can find one on eBay. Only thing you would need from there is a programmer.
I did find someone who would program and send me a replacement rom as long as I can provide the program to put on it. So far I cannot find any other information about the keyboard and rom code used for it. From what I can tell from other forums, it is a clone keyboard and not OEM from Apple. If I cannot find the program I may need to just purchase a working OEM keyboard off eBay or somewhere. Shame though as the keyboard is in excelllent shape otherwise and worked fine before my mistake.
There is a good chance that the EPROM code is readable and just an I/O port has been damaged.
If address and data is read-able, it's likely the ROM code can be extracted. (FYI)
FYI . you don't mention it but I assume you know that is not a factory Apple ][+ keyboard. It is a 3rd party replacement. The original factory ones used a different encoder setup and didn't have the caps lock ke or macro functions, etc.
I didn't mention that this is an aftermarket keyboard, but I did mention that it looks like it's using an 8748 chip.
That's a 1K eprom / microprocessor combo with two 8-bit ports built in, and if you're lucky, someone can read it to get the code from it and program a new one for you.
If you can't fix that one and end up buying a replacement, I'd be interested in buying that one as I could use one of the key switches and caps from it. I have a clone that uses a keyboard just like that one that has a key broken off.