CP/M source code released...

CP/M source code released...  I cut my systems programming (such as it was) teeth on CP/M, back in the '70s.  In the late '70s I actually published a highly configurable CP/M BIOS as a freebie.  You could say it was open source before anyone was calling it that.  I also worked with CP/M's publisher (Digital Research, founded by Gary Kildall) on the multi-user sequel (MP/M), which was pretty much a flop in the market, though quite interesting technically.