https://www.youtube.com/watch?v=hJNaAG2BXow
For those of us computer hobbyist that can remember the CP/M OS, this is a very interesting, revealing and sad history of the beginning and end of the CP/M OS (from Digital Research). Seems to me the CP/M OS was available to run on my Commodore 128 computer?? Edit - Yes, I just Googled and Wikipedia said the Commodore 128 was shipped with the CP/M disk, so the C128 would run CP/M and it's programs, if the CP/M disk was used during bootup.
Also another very good video, by the LGR Tech Tales, about IBM OS/2. Many fond memories for me, about when this OS was trying to compete with the Windows OS.
https://www.youtube.com/watch?v=wQdK9owqVd0
Thanks for the recommendations. I don't remember much about CP/M. But I do recall that ARM-based chips were the same ones used for the Risc OS which was supported on the European home computers (Adam or Acorn, don't remember which). We owe a lot to these older OSes, even those that didn't make it.