I already described how I diagnosed and fixed my MicroKim. using the KimStar subproject of L-Star: basically a Propeller QuickStart board, connected to the expansion bus of the MicroKim. I had my MicroKim working again, so I sort of shelved the KimStar project as "finished".

Then I found out that Aart Bik (a fellow MicroKim owner, retro enthusiast and immigrant from the Netherlands) was writing some MicroKim tutorials. I felt like playing with my MicroKim so I powered it up, but it had stopped working again. Never fear, KimStar is here! This time it turned out that the Rockwell 6502 that I got with the MicroKim (produced in 2003) had given the ghost. I replaced it with an MOS 6502 from 1982 and it worked fine again.

Then I thought: while I have KimStar and the MicroKim together again, let's make something that's truly useful. Somewhat ironically, though this version of KimStar is possibly the most useful yet, the software is also the simplest ever in the history of Software Defined 6502 Computers: The code's main purpose is to emulate a 24 KB (kilobyte) RAM expansion, and map it into the 6502 address space. There's also a cog to control the on-board address decoder but for this project it's basically configured to do the same as the on-board address decoder. Oh, and the Microsoft BASIC interpreter for the KIM-1 ("KB9") is preloaded in the RAM area when the Propeller starts.

The result is that I can now power up my MicroKim and QuickStart, and instantly use the BASIC interpreter by jumping into it from the monitor program. I don't have to download it via the terminal emulator first, so that saves me probably 3 minutes every time I want to use BASIC. And if I don't want to use BASIC, I can simply overwrite it; after all it's in (simulated) RAM, not ROM.

The setup is the same as described in the project description. The software can be downloaded at https://github.com/jacgoudsmit/L-Star/tree/master/Software/KimStar/4-BasiKim .