Posted By
crock
on 2015-09-06
07:13:38
 |  Re: Plus/4 repair
Hello!
The design of the +4 architecture is such that a completely failed RAM usually stops the whole machine as each ram chip is wholly responsible for 1 of the 8 bits. It's unusual (but possible) for a RAM to fail across only part of the address space. The fact that you have repeated blocks makes it more likely that it's an addressing problem.
Also, you appear to be able to run software? Did you manage to load something from tape or disk? If so, it makes me think that RAM from the CPU's perspective is OK, so it's maybe just an addressing problem from the perspective of the TED chip. If you have some pins rusted through, I would try to vary carefully check that the TED is seated and making good contact with the socket.
cheers, Rob
|
