Working with a 486 computer - Part 1

Working with a 486 computer - Part 1


This article marks a start of a series, where I try to build and work with a computer equipped with a 486 based PC. My goal is not to make the best gaming or the most accurate setup for that time and I dont want to get super rare parts just for the sake of having it. I want to dive into the world of retro PC computing, without having to spend money on expensive parts. I want feel the challenges people and IT technitiancs were facing at the time and follow interesting solutions to certain problems. In spare time I may run some games (sometimes with clunky controls), network machines together for multiplayer. I also like to repair things and solve probmblems that may arise duing the setup. it wouldn’t be involving work, if everything would work as planned! It’d rather be a miracle.

In short, the goal of the series is to build 486 based machine, and have some fun in the process. I’m going to start with explaining my motivation, move to parts selection, fixing ordered parts and finish with first boot.

Thinking of the past

An idea for having a 486 based machines comes from a friend, with who I use to chat from time to time. He put together an ISA keyboard controller for his 386 compatible motherboard. His motherboard does not support a PS/2, so he had to include his own solution. Beyond that, he also hacked BIOS and build a small board, which allows him to switch between original and hacked BIOS. It impressed me a lot, showed me how hackable old hardware can be. While I dont understand (yet) deep priniples on how it works, I got be back into retro world. There are interesting things one can do with old hardware, and some areas may be even unexplored or long forgotten underneath layers of dust.

A few years ago, I’ve gotten into retro PC world. I have an AT desktop PC, and a dual Pentium III server board, and I fiddled with them every now and then. It wasn’t permanent however, since I had to combine studies and work. I’ll write about those machines other time.

I’m not going to deep dive into hacking (EEP)ROMs and building custom PCBs, my experience and knowledge is nowhere near that level. I’m however experienced with electronics to a certain degree, so I can diagnose and fix basic issues. Having electronic repair skill, even a small experience, is a requirement, since old hardware may malfunction sooner or later.

Making the past part of my own reality

So my thoughts were set, visualizing a future retro PC setup in my mind. I wasn’t dead set on certain hardware though. I didn’t force myself into having a 8086 processor, I wanted something that was available on second-hand market and was relatively cheap. I could take a part in actions, however this would mean I’d have to wait and pray I wasn’t outbit at the last second. I also looked at damaged parts, which were cheaper, but may require some work. So I went instead with sure picks, where I could have purchased parts on next business day.

There was also an issue of used space. I have a small room, which is already filled to the brink. Sure, nobody stops me from buying a mainframe, but tripping on it everytime you enter a room isn’t very good for me and everyone else inside my home. One other thing, having a tidy and clean room is a blessing.

So I’ve searched the Internet for interesting looking offers. For starters I’ve been looking for a motherboard and a CPU. I had a known good AT power supply from other desktop, so I didnt worry about it.

I didnt have to look too far to notice a Socket 3 motherboard, equipped with Cyrix 486DX2 66MHz processor. It looked very good for me, even with a leaked CMOS battery, which has spilled alcaline near keyboard port. A leaked battery doesnt always mean a bad news, but in some cases it may cause a motherboard to be very hard to fix. In this case, leaking was mild, so I was willking to take a shot at it and fix it.