The many derivatives of the CP/M operating system
Its new licence says that "CP/M and its derivatives" are free for anyone to modify and redistribute. But which derivatives?
The original Intel 8080 version of CP/M had a relatively brief reign: it appeared in 1974, just seven years before the IBM PC launched with PC DOS. The PC, and its many clones running MS-DOS, rapidly outsold and replaced CP/M.
But still, CP/M was, for a while, the industry-standard microcomputer OS, making Digital Research a powerful and important company. Wealthy companies that lose dominance over a market they formerly controlled don't tend to just give up. Digital Research put a substantial R&D effort into expanding and enhancing CP/M, creating a large family of OSes. It had some significant wins and big sales. Some of those products are still in use. All those products are arguably "CP/M derivatives", and as such, Bryan Sparks' 2001 edict might have just open-sourced them all.