Diagnosis

Soooo.......... Yeah....

I plug everything in and it's doing.... something. Just not running the Hello World program stored on the EEPROM. It definitely gets through the initialization part of the program, because I can see it turn on the cursor and reset the screen to the top left corner.

So some data is flowing out of the EEPROM, into the CPU and then into the 6522 to the LCD.

Cue the sad trombone. Now I get to start diagnosing this thing. I've already got one bodge wire on the back to give power to the 7400 chip, so let's start building some stuff.

I'm not 100% sure where to start, so, let's attach the Audrino to it so I can read the bus......
Crap.
The audrino program reads on the rising edge of the clock and.... I have no way to know when that is.

That was the smallest prototype board I had on hand and didn't want to cut anything at the time.

First, I added the yellow LED with a resistor (hiding under the board in this photo) so I could see if the clock was running, and at what speed. Turns out I have a pretty good range with that 555 setup.

Seeing that the clock is running, I thought maybe I could just aligator clip into the clock pulse, but then I looked at the wiring setup to make the audrino read the data bus, and I realized that I was going to need at least three pins, so I just made a breakout board for the three I needed, and also +5V because I was tired at the time and thought I needed that as well. At least it's there now.
So I needed access to a common ground, the clock, and although not actually necessary to make it work, the audrino does also read the state of the Read/Write pin, which I'll want for diagnosis anyway, so I added that. Red/Black are standard, I've always used white for the clock signal on my breadboards, so I carried that over, and yellow for control lines, so I used that for RWB.

I started it up again to make sure my bodge wires and breakout board didn't just mess things up farther, and it functioned exactly the same. Time to attach the Audrino.

I got everything wired up and then realized I needed a second USB cable so I could power the computer, since I stole the one from the Audrino. I have one upstairs, but believe it or not, all those dupont wires are hard to get lined up and inserted just right, and I have a pack of 10 new 74LS00N chips arriving tomorrow (I broke the power pin on the one I had from my 6502 kit, so I ordered more), and rather than try to diagnose it with the 74HCT1000 that is in there as a temporary replacement, I'll just wait for the right parts to arrive. One less thing to worry about.

I have no real clue what to expect yet, or where diagnosis will even start. If I see it start running and fail, I guess I'll have a starting point. Honestly, I'm surprised I'm not farther, but this is a whole new skillset for me to learn, and I'm enjoying every minute of it, even when it's a bit frustrating.