Today my copper plates arrived and I could finish up the construction of the driver role board. First up, however, was to test that the board I wired works properly. I whipped up some fpga code that would light the LEDs when various signals were high or low on input and that would emit a high output on a selected line.
Since I had 9 inputs but only 8 LEDs, I needed to use one of the pushbuttons to switch to the ninth input line. I need to generate outputs on 13 lines but only have eight slide switches on the board, so I used a second pushbutton to swap between the first 8 and the last five signals.
First up, I had to make sure my temporary fpga code was working correctly, before inserting the driver role board and testing it. That took a while to get all the signals for every device on the board working - DRAM, flash, VGA, PS/2, serial port, 7 Segment Displays, switches, LEDs, buttons, peripheral adapter signals, and the USB signals.
Now that it is working fine with the small extension board which allowed me to check the output pins and route an output to all the input ports, I am ready to wire up the extension board to power and do some testing at the end of the cable. I should see +5V on the output pins when I turn on each signal, and I should be able to detect ground and +5V as a 0 and 1 when I hook them onto the input pins.
It is late, so I will work on this over the weekend. I have an obligation on Saturday to be at the game museum, as we want a board member there every saturday but all my peers are on business trips or otherwise unavailable.
I will bring my computers and documents in order to integrate in the code that reads and writes to the onboard DRAM and implements my transactional control registers. These won't impact the testing of the cable at all, but will let me move ahead.