Replaced all chips that had tarnished legs and iffy solder joints; behavior is much better but not perfect

INCREMENTING AC SEEMS TO INCREMENT IN BOTH FETCH AND EXECUTE PHASES

This points to a timing or decoder signal not getting to the gates determining when to do the increment operation on the accumulator. In general the incrementing seems more reliable and the PC was stepping in single word increments before I added the memory board to the stack.

MEMORY BOARD ADDED INTO THE STACK

I decided to insert the memory board after removing the temporary wires from the front panel entry keys that had been driving the memory buffer (MB) register. I tried to do some deposit and exam operations, to check whether memory was working, as well as running instructions from there.

The PC no longer increments when doing any fetches. It cannot be loaded with a non-zero value. The memory contents show up in the MB as all one bits or sometimes half ones and low order zero bits. When I execute an instruction, it believes it is a TAD (op code of 000), which is not what I would expect when the MB claims to have all ones in it. 

I haven't double checked the cabling I did between boards, thus this may be a fault or faults introduced by putting the wrong cable in the wrong connector, but I will check that on the next break during my workshop time. 

DEBUGGING TO DO

I did not receive the extender board which makes it feasible to probe all the points on a board while it is working the machine. It will come with a later set of boards for peripherals of the EDUC-8. I can at least verify all the signals on the top board (T for timing). If they are wrong, the errors cascade downward to the rest of the machine 

When the T board is found to work completely correctly, I can find ways to tack wires onto some signals on the decoder (D), accumulator (A), program counter/adder (P) and memory (M) boards, but that will be very tedious due to the need to partially disassemble to wire up the temporary wires. 

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