After a month and a half, I returned to the ICs and wires, making the rest of registers logic and the register A.

Realized I was mistakenly connecting some ICs, as control inputs are active low (most TTLs are) and I have to put a bunch of 7004 (inverters) to make things work.

Now we have register A built and tested.

Almost all of my 14 breadboards were used (some for testing boards) so I ordered 6 more.

As a side note, I noted that the register was losing it's state when I turned off the desk light (!!!). One decoupling capacitor between Vcc and ground lines close to the IC seems to have corrected this issue. I'm afraid of what kinds of interference I will face when running this CPU above 1 MHz...

Some pictures to make this log entry more beautiful:

Thanks for reading.