Before Michael helpfully pointed me to a Microtronic on eBay, I'd been hunkered down trying to build my own from a picture of the schematic and a handful of ICs.

Here you can see a video of the first successful complete self-test.

It was this attempt to build a recreation that lead me to discover some errors in the ROM we had extracted.

The detailed story of how I got to this point is available on my website as Disassembling the Microtronic 2090.

The document covers a variety of Microtronic (dis)assembly topics:

• Dumping the ROM
• Disassembling the code
• Understanding the hardware
• Reading the SRAM
• Finding the "nim" game
• Developing a breadboard Microtronic
• Emulating a TMS1000
• Debugging the keyboard
• Correction by inspection
• Verifying the Microtronic speed
• Redumping the ROM
• Comparing with a real Microtronic

I'm currently working on tidying up the emulator code for the TMS1600 that executes the ROM. So hopefully soon you too can have your own faithful recreation of the Busch Microtronic 2090!

- Jason