I finished assembly and verification of the CPU card. After checking all connections with a multi-meter, I populated the board with IC-s and assembled simple power supply (5V stabilizer) and testing circuit (just 3 LED-s with resistors and a reset switch) on the bread-board. Then I burned test program on EPROM that just selects 3 of the I/O selection outputs in a loop and I put the EPROM chip in the board. The other 32K EPROM chip for now is not in the board. The test worked. See it here.
This test verified following basic CPU board functionality:
* clock circuit
* reset circuit
* I/O address selection circuit
Next step is to assemble the serial communication circuit on the bread-board and test the CPU and serial communication with a bit more advanced but still rudimentary operating system (Monitor program). After that, serial communication card assembly on a permanent board (I/O card).
|MKHBC-R1, back in business.|
|Chips populated, only EPROM to burn and face the truth.|