4690 OS evolved from Digital Research FlexOS, which replaced Concurrent DOS 286. The revised license for CP/M from DRDOS, Inc this month covers "CP/M and deriv

4690 OS evolved from Digital Research FlexOS, which replaced Concurrent DOS 286. The revised license for CP/M from DRDOS, Inc this month covers "CP/M and derivatives". DRDOS is a derivative of CP/M, as is Concurrent DOS/Multiuser DOS, and arguably the FlexOS line too.