MP/M 2.x

Multi-Programming Monitor Control Program (MP/M) was a multi-user version of CP/M created in 1979. It could run on 8080 or Z80 based computers. Eventually it was ported to the 8086 and was named MP/M-86. It eventually assimilated technology from CP/M-86 and became Concurrent CP/M-86, later evolving into Concurrent DOS.

Digital Research MPM-86 2.0 Source.7z,0.51 MB
Digital Research MPM-86 2.1 [CompuPro MPM 8-16 V2.1F] (8-inch SSSD).7z,0.11 MB