Last Christmas I was browsing eBay and happened upon an auction for a single 3’x4′ schematic for part of the IBM PS/2 model 30-286 motherboard. I have long been a collector of the IBM PS/2 series and while some of the schematics are available in SAMS Computer Facts I had never seen schematics for the 30-286, or for that matter, any of the later models. I was thus quite excited to see this schematic especially when it turned out that the seller had a large number of other schematics for the PS/2 series and other early personal computer products, none of which turned out to be easily available elsewhere!

After some negotiating I was able to get a good price on the whole lot of them. It turns out that they were published by a company called ‘Maintenance Information Technology’ which I have never heard of. By looking at them it is clear that some (such as the one for the Macintosh 800K floppy drive) are the result of reverse engineering, but others (such as those for the PS/2 series) have the pinouts of custom ICs on them which suggests that they might have had access to internal IBM schematics in some way. In either case, I wanted to make them available to the world, but, being a mix of ledger and 3’x4′, I didn’t have a scanner big enough to scan them so I had to send them out to be professionally scanned. The process, while somewhat expensive, went smoothly and is now done.

I have created a new section on this site for schematics like these. You can find it on the main menu under ‘Schematics and Resources‘. Feel free to redistribute any of this material. I am interested in seeing this preserved and redistribution will help assure that.

Here is a complete list of the schematics:
– Apple LaserWriter
– Apple Macintosh 800K Floppy Drive
– IBM 3179 Monitor
– IBM 3179A Monitor
– IBM PS/2 Model 30
– IBM PS/2 Model 30-286
– IBM PS/2 Model 50 (missing one sheet)
– IBM PS/2 Model 80
– Seagate ST251 Hard Drive

-Matthew