CAME INTO THE SHOP TO DEBUG THE CPU, NOTICED BIT 7 WAS FAILING AGAIN
I put the memory compartment covers back onto the system, now that memory was working (I thought). Previously I had the cover and side rails removed to give easy access to all cards and the core stack.
I intended to check a number of issues I was seeing with various instructions executing. I set up the scope for the first situation and toggled in instructions to execute. One I entered was going to use index register 1, thus it would have bit 7 set. I stored the instruction but when I executed it, there was no use of the register. I displayed the memory location and noticed bit 7 was zero. I tested by trying to store all ones and got the expected 0 in bit 7 and a parity error.
WILL HAVE TO FIND AND REPAIR THE CONNECTION PROPERLY
Touching the connection with my ohmmeter probe had temporarily restored connectivity, but that went away. I need to zoom in much closer and figure out the exact failure so that I can permanently repair it.
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