"A Lost #IBM PC/AT Model? Analyzing a Newfound Old #BIOS

GearTechWolf occasio­nally rescues and dumps random #ROM #chips that show up on eBay, and makes the contents available so they aren't lost to the ages. One of his hauls turned up two pairs of #EPROMs labeled 'IBM' in plain dot-matrix: one showing part numbers (and '© IBM CORP 1981,1985'), the other tagged with a specific date ('25/05/90')."

https://int10h.org/blog/2025/11/lost-ibm-at-model-bios-analysis/

#retrocomputing #dos #ibmpc

I have a #GEM S2 #synthesizer without the turbokit. It's amazing, but I was always been a little frustrated. Now after 30 years, I found a schematic of the turbokit and the EPROM dump: https://github.com/DitroniX/GEM-Generalmusic-S2-S3-Series-Synth-Retrofit-Turbokit

I am going to see if I can build my own. I redrawn the schematics in #KiCad. Everything went smoothly, but it has become difficult to source 27C4001 #EPROMs. DitroniX's project used a SMT version, that I find difficult to source. Maybe shall I get back to DIP?