I picked up a case from Free Geek Vancouver during their garage sale event on the 28th of April, 2018. Well, actually, I picked up a whole computer. The stuff they normally sell is a lot newer, but I asked about older stuff and they just happened to have this one lying around. It was a beast to drag through transit, but I managed to get it home. I then examined it, tested it, and ultimately tore it apart.
This Old PC
This was actually quite a fascinating machine. It looked to be in poor condition, covered in dirt with a cracked bezel, loose cover and loose drive cage. Upon closer inspection, it was actually remarkably intact. The dirt mostly washed off in the rain, the crack in the bezel is only skin deep, and the case is clean with virtually no rust (a big concern in a coastal climate).
The hardware inside was an interesting mix of early and mid 1990s. At first I thought this was an upgraded 386 machine because of how archaic the motherboard appeared. It has a combination of 16-bit and one 8-bit ISA slots, with no VLB or PCI. It only takes 30-pin SIMMs, and has what looks like a coprocessor socket. But then I looked closer at the CPU, which is a 486 Overdrive. I recalled that while there was a 486 upgrade for 386 machines, it was branded RapidCAD, not Overdrive.
In fact, it is a 486 system, though it is an early one and it has been upgraded. The motherboard is a “486wb4a” with an OPTi chipset, and that’s all I know about it. I was wrong about the CPU, too. Based on the markings, I had thought it was a 40MHz 486, a respectable processor for the early 90s but nothing particularly special. It is, in fact, a DX4 Overdrive clocked at 100MHz. Very cool, though maybe a bit limited by this motherboard. It has 8MB of RAM, which might be the max for this board, and I have no idea if that was a lot for the time or limiting even then.
Most of the system is serviceable, but unremarkable. It has an ATI VGA Wonder of some description, which is probably perfectly fine but it’s only an ISA card which will be at a disadvantage compared to its VLB and PCI brethren. It has an Acer-branded (did they make cards back then?) multi-IO card with two serial, one parallel, floppy, single IDE, and, oddly, a game port. There’s a Sound Blaster 16, clearly a later upgrade, but it’s a thoroughly mediocre Vibra-based CT2800. I was kind of hoping for a better variant or some neat-but-impractical weird clone. The modem I know nothing about, and it’s badly bent from the drive cage resting on it. Finally, it has the simplest IDE card I’ve ever seen (4 DIPs of glue logic and an audio passthrough) for the CD drive.
The drives might come in handy. The 3.5″ drive works, and though I have one it’ll be good to have a spare. The CD-ROM is far more appropriate than the 2009-era DVD burner I have, and it appears to be IDE so it should work. And I’ve kind of always wanted a 5.25″ drive. I have no practical use for one, I have no 5.25″ floppies, but it’s just a cool piece of retro tech. Sadly, there was no hard drive with weird old stuff on it to investigate.
Oh, and the machine still works. Or, at least, the core components did. I pulled out everything except the motherboard, CPU, RAM, videocard, and multi-IO. After verifying that it POSTed, I plugged in a floppy drive and booted DOS. I then realized I had nothing interesting on actual floppies and tried out my Gotek emulator. That turned out to be a great purchase- it worked great and I was able to try two versions of DOS along with cachechk and speedsys.
I felt kind of bad tearing it down for parts, but in fact there are two serious problems with the computer that really need to be addressed.
The first is the power switch. It’s broken. It does still sort of work, but the machine only turns on if it’s nudged just the right way. It makes arcing, sparking noises that are frankly quite scary when I try to get it into the sweet spot. AT power switches carry full mains voltage, so this isn’t just annoying but a possible safety hazard. I’m hoping that one half of the switch is still good, because that’s all my new ATX supply needs.
The second is the leaking clock battery. It’s a problem that’s sadly all too common for boards of this era (and what killed my last 486). Fortunately, in this case it’s only caused a little bit of cosmetic damage, but that battery needs to go ASAP.
In case anyone is curious, here’s a parts list made to the best of my ability.
- “486wb4a” motherboard, OPTi chipset
- Intel 486DX4 Overdrive processor (at a blistering 100MHz!)
- 8MB of RAM (8x1MB?)
- Acer-branded multi-IO card (2 serial, 1 parallel, 1 joystick, 1 floppy, 1 IDE)
- Future Domain Corp IDE controller (very minimalistic)
- ATI 28800 (VGA Charger? VGA Wonder?)
- Sound Blaster Vibra 16 CT2800
- Modem of some description (8-bit ISA, badly bent)
- Big 5.25″ floppy
- Fujitsu 1.44MB floppy
- Creative 6x CD-ROM (IDE, made by Funai in Japan)
- 200W AT power supply
- A case that we will be using
The Next Step
We’re getting close, real close! I want to do one more round of bench testing and hack or replace the Dallas RTC, then it’ll be all ready to put together in my new old case! That’s far from the end of the project, of course, but I’m really excited to go from a pile of parts to a nice computer.