The IBM PCjr BIOS is very well documented in the IBM PCjr Technical Reference manual (a must read for every PCjr developer).
The only problem is that navigating that code is not easy. It has all the problems from scanned books:
- the fonts don’t look good
- no hyper-links
- and difficult to search
So I dumped the BIOS and started analyzing it with IDA Pro – Free version. I added some of the original comments from the Technical Reference manual, and added some comments of my own.
If can browse it using either:
- IDA Pro (the .idb file): bios-f0000-fffff.idb
- or by looking at the .lst file (just a text file): ibm_pcjr-bios.lst
Or just clone the project from github: https://github.com/ricardoquesada/bios-8088/tree/master/ibm_pcjr
This is still Work-in-Progress. I add comments in “let’s see how this portion of the BIOS work“-basis.
BTW, the Tandy 1000HX BIOS dump is here: https://github.com/ricardoquesada/bios-8088/tree/master/tandy_1000hx
Update: Updated links