MP/M led to Concurrent CP/M-86, which in turn led to three separate families of OSes:
• Multiuser DOS (native 32-bit multiuser multitasking DOS-compatible).
• DR-DOS (DR's comeback, a better DOS than MS-DOS, available at retail, which spurred MS into creating MS-DOS 5, then 6, then Windows 95).
• DR FlexOS: realtime multitasking with a GUI, used widely in the embedded industry for ~40 years and still supported on some IBM point-of-sale terminals in the 4680 and 4690 range.
• Multiuser DOS (native 32-bit multiuser multitasking DOS-compatible).
• DR-DOS (DR's comeback, a better DOS than MS-DOS, available at retail, which spurred MS into creating MS-DOS 5, then 6, then Windows 95).
• DR FlexOS: realtime multitasking with a GUI, used widely in the embedded industry for ~40 years and still supported on some IBM point-of-sale terminals in the 4680 and 4690 range.
I wrote about the extended family:
https://www.theregister.com/2022/08/04/the_many_derivatives_...