Part 4 - The Testing

 

First Test - Front and Mother Boards

After careful checking and rechecking before and after each component it was time for the 'smoke' test. Connected the two boards together and they went together really well. The put 5 volts to the motherboard. No IC's had been installed yet, just in case there was something really wrong. Putting on the power did nothing 😡 no 5v to any of the IC sockets or 5v to anywhere for that matter. A problem was found on the motherboard, a through hole pad for the 5v didn't go through. It appeared to a problem on the PCB drawing, not the manufacture, but a short link from the 5v in to the connector that feeds the power to the front board sorted it.

When that was fixed all the LEDs on the front that should be on came up nice and brightly. Then following the instructions shorting the ground pins for the other LEDs proved that they worked.

Next will be the next test. Still need to add the ICs yet.

Second Test - Timing/Control, Decoder and Accumulator boards

The testing of these boards is a bit more complex see page 26.

Set up

• Make a temporary connection between SR07 pads on the front panel to MB0-7 pads left of the motherboard.
• Turn on the power. The 'FETCH' LED all the PC and MA registers should be on.
• Because the MB register is wired to the front switches. Flicking the switches will change the MB LEDs, up with light them up.
• The AC register may have some random LED's don't panic, this is normal.
• Set the FAST/SLOW switch to SLOW, up.
• Set the SINGLE/CONT switch to SINGLE, up.
• This will set to slow with single stepping.
• Make an AND instruction by setting all SR switches to 0, down.

Testing the FETCH-EXECUTE cycle

• Press the RUN key.
• RUN LED should light up and the FETCH LED should still be on too.
• FETCH LED will be on for about 12 seconds then go off and then the EXECUTE LED will come on.
• AND LED should be on also.
• After 12 seconds these LEDs should go off and back to FETCH.

During the EXECUTE cycle if there is a number other than 0 in the AC register it would be shifted around 8 bits to the right.

Testing the indirect addressing

• Set SR4 to 1 to emulate indirect addressing.
• Press the RUN key.
• This should make it run as before but the DEFER LED will be on for 12 seconds before the EXECUTE LED

Testing the TAD instruction

With everything set up as above set SR5 to up to simulate a TAD instruction.

Press the RUN key and should be the same as AND but this time TAD.

All other primary instructions can be checked the same way by using SR5,6,7 and observing the centre cluster of LEDs