I’ve Built a Computer

Here’s when it was more “in progress”

Perhaps evident from this picture, that the 16K of RAM in the top right is still not connected. This means it’s still barely a computer, since input doesn’t matter to it, the output is clearly screwed up, and it can’t operate on anything larger than the registers of the processor can handle.

I had spent over an hour looking at this right here. I was, as it calls it, in “Hell”. I had reflashed the ROM, hooked up an Arduino Mega to the data bus leaving the VIA, everything seemed exactly like it should. I then checked the inputs to the VIA coming from the data lines from the 65C02 and those were good too. I’ve tried different clock speeds, tried resetting it, tried reseating the screen and the wires.

Eventually I had given up. I had a blue screen on hand and wanted to see if, and how, it differs from this.

Generally this type of testing is known as a “known-good” test, being that I know my circuit is perfect, so I can test screens with it. On the flip side, I can test my circuit with known good screens. I didn’t know if it was my circuit OR my screen, so it was possible this does nothing…

But, tearing out the one that came in my kit and throwing mine in there has worked flawlessly. Apparently the kit one was broken. This would have been awful should I have not had one on hand to test and thought it was a “known-good” unit.

At that point, this is how I felt.

I had also socketed the EEPROM, and finished up the RAM. This makes it so I don’t wear out the breadboard with ins and outs, and it is stood off a touch to allow easier access. My wiring is no where near as tight as Ben Eater’s, but it works and it wasn’t anywhere as frustrating as it was when I was trying to emulate that. At some point, I’d like to find a card-edge backplane that can hold enough signals for me to perhaps get away from the breadboard setup.

I also upgraded this to 1MHz and I use a Dupont jumper to switch between this oscillator and the manual stepping / slower 555-based clock. I may make a front face for this and migrate all of the switches to that.

I also didn’t consider character count of common displays when I bought this domain. :shrug:

Sorry for the blur, Samsung makes terrible phones.






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