Finally picked up the Atari 2600 again. I found someone selling a unit with 100 games for $100 in town. I managed to score it for $75 but it only actually had 60 games.. Still turned out to be 40(ish) games I did not have before. and Sadly that Atari did not work. (Discussed with seller and we agree’d it wasnt an issue because the games were what I was after, but hey. another to sort out right…)
however of course I want to be able to PLAY these games… I’m tired of emulators. I took the WIP unit out of the box, re opened it and decided to finish it. this whole thing really should have been like an hour project one afternoon, not sure why I shelved it. But I wired the transister boost I built previously, gave it power, a game and turned it on. wow… whats that nasty hum… oh wait, theres a short for sure!….
20 minutes and a ton of tests for shorts/etc later I discovered when I made the original circuit, I put the transistor in backwards… on top of that I for some reason put the ground on the video in and the video in to VCC. not smart.
oh well. disassembled that bit. reversed the in and out lines so the transistor was correct, and tested again.
and Voila! things are running. Before looking at the photos, I KNOW I need to work on my photo skills and my phone is NOT a suitable camera. I’ve previously liked the details of the mod I installed and how it works, so feel free to go look at that post here
if you have any questions or just want details, please feel free to reach out to me. I can create a schematic and wiring diagram for anyone that isn’t satisfied with the link
And finally a horrible video of it working
when I was little I was always fascinated with how things worked. and back in the TRS-80 days it was simple and clear. well things have progressed GREATLY since those days, and its a lot less understandable to the base user these days. you add this nostalgia to my wishing to flex my school knowledge some in the decades since and I came up with this…
So I started building my device using a program called Logisim I’ve had some issues loading the site lately so heres the direct download on Sourceforge. once I started progressing with that I realized its not even USABLE. short of manually setting the logic/etc and watching the output and using an excel sheet manually its not what I wanted. so naturally I took the big leap into something I knew very LITTLE about which has the power to do what I want (realize the actual CPU).
So as much as this is me building a CPU and yes I will demonstrate every piece for you as I do this in logisim, I will also keep the FPGA code base up on GIT with it so you can see and learn with me.
First off, I do NOT expect this to be overly useful to anyone for anything real as it’s an old school 8 bit CPU, and I expect about as much power as the old Z80. It will be nice to at least say “I DID IT!” but who knows, maybe one of you will take the base learning and turn it into something real world with some actual power.
Now for starters. the base of the CPU is going to be the ALU (Arithmetic logic unit) and in my design i’m going to start it with the basics. lets ADD something.
Watch for the next post where we start the actual work.
So, every now and then I like to check our our local “good will” style stores. Here in Ontario we have Value Village and the Salvation Army as well as a few others. On these trips I often find some cool things that I take home, restore and resell or keep, but every now and then there’s something that you just cannot turn down. This visit happened to be one of those visits. I scored a complete Compaq Portable III. No idea if it worked or anything, but for $15 CAD it’s worth the score.
I will be tearing it down and doing a complete restore, so keep watching for the Portable3 tagged posts.