Francis Bauer

It appears that the waveforms for the key presses look fine. At this point I suspect that U24 is flaky. You could try removing U24 and carefully bending pin 17 and one of the other keyboard col pins (18,19 or 3) so that when you reinsert U24 those pins don't go into the socket. You can then by using a couple of wire jumpers with clips, try switching the suspect col with the another col to see if the problem follows the switched pin or if it stays the same. Connect the other end of the jumpers to...

Interesting problem. To verify resistance/switches how about carefully connecting one of your DMM probes to the R161 resistor leg (where you have been placing your tweezers) and the other probe to pin 17 of U24. Measuring resistance (board powered off), what do you see when you press the 4,5,6,B, DEC, FREQ switches. They should all measure about the same when the switch is pressed, something low, less than a couple of ohms. Now move the probe on the R161 to its other leg (GND). Now what do you measure...

Congratulations on getting your SBC Relay computer mostly working. Usually when you have a problem like this, where something starts working when you probe it using a metal object, you (your body) is supplying additional capacitance/noise into the circuit. This is usually an indication that there is a solder connection or printed circuit board trace problem and that the circuit doesn't have a good low resistance connection. Do you have a DMM (Digital Mulitmeter) that you can use to measure the resistance...

Way cool Ryan, good job in packing instructions/memory to the max. This version gives the player plenty of time to make their moves. Reminds me of writing/playing a version of Pong I called Hard-Copy Pong, where instead of using a CRT each "frame" was printed on the line printer. Talk about giving you plenty of time to make each move...

As per the documentation the save/restore functionality is limited to the lower 128 bytes. So unfortunately this limitation is as designed. Snippet from Keypad section of the documentation: Save / Restore memory (RAM) to non-volatile storage (EEPROM) <freq> <dec> Restore memory from non-volatile <freq> <inc> Save memory to non-volatile Note: (Only lower 128 addresses are saved / restored).</inc></freq></dec></freq>

Ryan, Your case looks great. Including the layout on the back is awesome. Thank you for sharing.

It is interesting that the first 'st' command is able to store a 90h into memory 00h, but the 2nd 'st' command doesn't store E9h but 21h into memory 01h. Try manually storing values into memory. You can do this from the unit's keypad: 00 ADR 00000090 INC 000000E9 INC Now do a 'd' (dump) and see what the values are in memory 00h and 01h, they should be 00000090h and 000000E9h. Let us know what you see. Try single stepping through the program and watching the LEDs on the unit to see if you can see...

It is interesting that the first 'st' command is able to store a 90h into memory 00h, but the 2nd 'st' command doesn't store E9h but 21h into memory 01h. Try manually storing values into memory. You can do this from the unit's keypad: 00 ADR 00000090 INC 000000E9 INC Now do a 'd' (dump) and see what the values are in memory 00h and 01h, they should be 00000090h and 000000E9h. Let us know what you see. Try single stepping through the program and watching the LEDs on the unit to see if you can see...