So I've got a IIc here, starts up with random characters on screen and the built in self test throws out RAM ZP 01000000. I went ahead and replaced RAM #MRD6 and now it shows RAM 00100000. I found this strange and piggybacked MRD5, resulted in RAM ZP 10000000 (MRD7), piggybacked that one too and it just goes up the ladder into the auxiliary bank with *RAM 0.... .
Any suggestions? Should I suspect the MMU?