August 2022 – The Quarky Engineer

Moving forward in time a few years – I also had an old 386SX motherboard that would not turn on. Sure enough one of the traces was damaged by the battery leaking. It seems like 70-80% of the 386 era motherboards have now failed because of this exact problem. So many of them used a Varta NiCd battery that eventually leaks, and the leak almost always eats traces.

Fortunately there was only one trace that was damaged bad enough to need a patch. I soldered in a patch and the board POSTs. A quick bath in the ultrasonic to clean up some corrosion as well. 8MBs of RAM in this one, so it would have been a nice machine back in 1989. I had a 386SX machine during part of college, so good memories with this.

I’ll have to look around and see if I have a 387SX in my parts bins.

The XT-286 (5162)

August 31, 2022 Jeff

This has been an interesting resto-project. While there are a good number of IBM PCs, IBM XTs, and IBM ATs still floating around, you don’t see very many IBM XT/286s. It was a computer IBM released after the first IBM AT came out, and it was an XT sized case with a 80286 motherboard similar to the IBM AT 5170 but sized to fit. It has a 6Mhz 80286 like the first AT, but is ever so slightly faster due to 0 wait-state memory.

The one I have is pretty amazing condition and with a very original configuration. It has the original factory installed 20MB hard drive (ST506) as well as the 1.2MB 5 1/4 floppy drive.

There is only one BIOS revision from IBM for this platform, and it does not with with the XT-IDE-CF ISA card (which gives you a compact-flash based hard drive). I pulled the EPROMs for the BIOS out and repalced the BIOS with a period correct AMI 286 BIOS, and that allowed the XT-IDE-CF to work correctly.

It has 640k, which we all know is more than anyone will ever need. 😉

I have the CGA output going into an RGB2HDMI converter that drives a display, so you get those awesome 4 color graphics!

The memory and the machine test out fine, which is pretty cool given it was first sold in 1986, 36 years ago. It was $2500 back then, which would be about $6400 now. Premium!