Wow. Its been over a year since I last posted anything. Over the past two years, I’ve been working as the project manager for a large software/infrastructure implementation, so that has taken up most of my time. That project started a month or two before COVID hit and we basically powered through the entire pandemic with our primary team on-site for all but a few weeks when our state issued a shelter in place order.
I guess its my turn to jump on the #septandy bandwagon. #septandy is where retro computing bloggers and youtubers take a look at tandy gear in the month of September. I picked up a tandy color computer 2 with a tandy tape drive on ebay a while back and hadn’t gotten around to testing it out. The coco2 only has RF out and the only RF device I had available was an old VCR.
After building Ben Eater’s 6502 computer, I wanted to try my hand at my own version. I wanted to utilize the full 32k of ram and use a real monitor as the display. I started with a W65C02 processor and an AT28C16 eeprom. I filled the eeprom with nop instructions and set the eeprom to the top of the memory map. I’m using the same slow clock module and Arduino sketch from Ben Eater to view the address and data buses in real time.
I’ve got a few of these old portable CRT TVs laying around and I thought I might use one of them for a display for a homebrew computer I am working on. The computer outputs a composite video signal, but these TVs are RF only, so I figured I’d try to mod one to add composite in. The TV I went with is a Bentley 100C. Mainly because I like the way it looks.
I finally had a few days off over the holiday weekend and was able to follow along with Ben Eater’s 6502 computer series on youtube. The videos series is well done and the build was pretty straight forward. The schematic for the final computer is below. I didn’t take too many pictures of the build process. I did start out with a different breadboard layout, but it was getting a bit cramped, so I built out the address and data buses down one side of the breadboard which made things much easier.
I picked up this c64 a while back at an estate sale. It was stored down in a damp basement and was pretty well coated in dirt and grime. Unfortunately, I didn’t take a picture of the case before I cleaned it up, but trust me, it was gross. After testing it, it did work without issue. Well, the VIC is pretty bad. The video quality isn’t great, but it does work.