PDP-8/M Rebuild – part 4 – Reassembly and first power up

00001.jpgHaving reinstalled the power supply into the chassis, the console was put back into slot 1 and carefully reassembled.

The minimum board set was then installed consisting of:

  • Slot2: M8330 KK8-E timings
  • Slot3: M8300 KK8-E major registers
  • Slot4: M8310 KK8-E major register control
  • Slot 20: M8320 KK8-E bus loads

The machine was then powered on and LEDs on the console sprung into life. Some basic operation from the console was possible (I was able to set the PC) although bit 5 of the PC appears to be stuck off. I will have to investigate whether this is a fault on the console or not.

I also installed an 8KW core memory set and retested with this in place. With these boards in place, the PC was all bits high and could not be changed.

So still some way to go! The next step will be to establish if the KK8-E is fully working and track down the issue that is causing the bit 4 of the address bus to appear stuck low on the console.

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