Going Back in Time

by Robert Nov 27, 2019 8-bit hardware electronics

A few years ago, I started watching a series of YouTube videos by Ben Eater. He was constructing a computer from first principles and providing his watchers an excellent course in computer-age electronics. Luckily, by the time I started watching, he was about half way complete with his series. I say this because I had a hard enough time waiting every few weeks or so for another in the series to be released. I was certainly hooked. By the end of the series, I knew I wanted to make my own or at least something like it. I procrastinated some, mostly due to not having the workspace to do a project like that in and getting the parts would cost a few dollars. So I left it aside for a while.

But I had gained a real itch for exploring and creating how computing used to work. Mostly I'm a software guy, by trade and by hobby, but knowing more of the computer engineering fundamentals has always been interesting to me. So I started looking around more. I was also watching videos by The 8-Bit Guy. He does lots of great work, but I was especially interested in the vintage computers that he would restore and fix. Something about watching something so old come back and look brand new again was very satifying. He once did a video on the Gigatron computer which I fell in love with immediately. It's a homebrew computer made without any dedicated CPU or graphics chip; just out of 74xx series ICs. And with some careful and clever engineering by its creators, it comes alive with the power of a late 70s computer, akin to the Apple ][.

After seeing that video and drooling over their website for a while, I finally bought the kit for myself. When it came, I was so excited to put it together. I had never done much soldering at all. I had an iron and had used it just a few times, but this was a much larger project. But, since they provided such detailed and step-by-step instructions, even I didn't feel lost. I think I managed to put it together in the span of 3 weekends, working several hours at a time. Only once did I get stuck for a while. I had most of the machine together, and the test LED pattern had stopped working. Luckily, I had a multimeter and was learning how to use it to troubleshoot the problem. Someone had kindly posted a whole spreadsheet of voltages that each pin of each IC on the board should be getting. Along with the schematic that was provided in the Gigatron manual, I was able to discover my mistake. I had accidentally soldered one of the chips upside down on the board. After feeling like an idiot and fixing the problem, everything was back to working again.

I had a good deal of fun playing with the machine once it was built, but I was addicted to the process of building it, I found. So, before too long, I started looking for other similar projects. One of the podcasts that I listen to had discussed briefly the PiDP-11 which seemed to fit right into my wheelhouse. This was a modern day recreation of the front panel of a PDP-11/70. It's creator was so dedicated to getting all of the details and just reading through his story about the computer's creation is impressive and inspiring. I ordered this kit too and put it together. I think I was done in less than a week which was disppointing in a way because I wanted more. But having it set up on the desk and watching the lights blink was a whole other reward as well.

After completing both of these projects, I ended up taking them into work to display on my desk. I got a lot of comments from folks who were interested on what they were which was always fun to talk about. Eventually, I once again had the itch to build something. Finally, after all this time, I decided I was going to build Ben Eater's 8-bit computer on a breadboard. To my delight, he had recently made it even easier to do. He started to sell the full kit on his website which was awesome. I ordered the full kit and began to put it together. This one was a much larger project in terms of time required, which is great for me. I still haven't completed the whole thing, but I've had a blast taking many hours over the past few months to build a piece here and there.

Building these projects has taught me a lot about electronics and has just been really fun. I don't regret my life of software one bit, but I'm very glad that I now have a whole other hobby that still lets me play with computers.