MP/M II

MP/M

Company type	Operating system
Industry	Computer software
Founded	1979
Founder	Tom Rolander
Products	MP/M-80, MP/M-86, MP/M-286, MP/M II

MP/M (short for Multi-Programming Monitor Control Program) was a multi-user iteration of the CP/M operating system, created by Digital Research's Tom Rolander in 1979. It allowed several users to access a single computer through distinct terminals.

For its era, MP/M was technologically sophisticated, offering a priority-based multitasking kernel—referred to as the nucleus—that included memory protection, simultaneous input/output management (XIOS), and capabilities for spooling and job queueing. This enabled users to execute multiple applications concurrently and switch between them seamlessly.

MP/M-80

The 8-bit variant operated on an Intel 8080 or Zilog Z80 processor with a minimum of 32 KB RAM, though this limited the memory available for running programs. To overcome this, MP/M utilized bank switching to alternate memory banks within the CPU's addressable range, allowing support for larger software. This approach was later incorporated into CP/M 3.0.

Interestingly, MP/M gained traction as a "power user" version of CP/M for individual users because of its multitasking and expanded memory features.

MP/M II 2.0 (released in 1981) introduced file sharing functionality, while MP/M II 2.1 (January 1982) enhanced the system with extended file locking.

Release history:

• MP/M 1.0 (1979)
• MP/M 1.1 (January 1980)
• MP/M II 2.0 (July 1981; added file sharing)
• MP/M II 2.1 (January 1982; added extended file locking)

MP/M-86

Similar to CP/M, MP/M was adapted for the 16-bit Intel 8086 processor, debuting as MP/M-86 2.0 in September 1981. Among its principal developers was Francis "Frank" R. Holsworth, who later became a marketing director at Digital Research. Known versions of MP/M-86 2.0 are dated September and October 1981, with MP/M-86 2.1 following in July 1982.

The MP/M-86 2.1 release incorporated elements from CP/M-86 1.1 (BDOS 2.2), evolving into Concurrent CP/M-86 version 3.0 (BDOS 3.0) by late 1982; this update introduced features such as "virtual screens." Kathryn Strutynski continued her role as project manager overseeing Concurrent CP/M-86 development. In December 1983, an optional DOS emulator called PC-MODE was launched for Concurrent CP/M-86 3.1 (BDOS 3.1), which shipped in February 1984. This platform eventually transformed into the MS-DOS compatible Concurrent DOS (BDOS version 3.1 and above), further evolving into FlexOS and Multiuser DOS, systems still operational within some industrial environments.

The abbreviation CCP/M commonly refers to Concurrent CP/M.

MP/M 8-16

MP/M 8-16 or MP/M-8/16 was CompuPro's designation for integrating multi-user capabilities of the 16-bit MP/M-86 single-task CP/M environment with the multi-user, multitasking functions of the 8-bit MP/M on their multi-processor hardware platform. This configuration later supported Concurrent DOS 3.1.

MP/M-286

In 1982, Digital Research revealed plans for MP/M-286, designed to exploit the Intel 80286 processor’s memory management and protection features to run both MP/M-86 and CP/M-86 applications efficiently. Although it never appeared as initially intended, it evolved into Concurrent CP/M-286, which laid the groundwork for Concurrent DOS 286 in 1985 and subsequently FlexOS 286 in 1986.

Commands

The MP/M II Console Command Processor (CCP) accommodates the following set of commands:

• ABORT
• ATTACH
• ASM
• CONSOLE
• DDT
• DIR
• DSKRESET
• DUMP
• ED
• ERA
• ERAQ
• GENHEX
• GENMOD
• GENSYS
• LIB
• LINK
• LOAD
• MPMLDR
• MPMSTAT
• PIP
• PRINTER
• PRLCOM
• RDT
• REN
• RMAC
• SCHED
• SDIR
• SET
• SHOW
• SPOOL
• STAT
• STOPSPL
• SUBMIT
• TOD
• TYPE
• USER
• XREF

CP/NET, CP/NOS, MP/NET, and MP/NOS

During the early 1980s, Digital Research introduced CP/NET, a networking solution that enabled an MP/M server to interface with several CP/NET clients operating under CP/M. Developed by Tom Rolander, CP/NET provided functionalities such as file and printer sharing alongside electronic mail services.

MP/NET enhanced MP/M by incorporating network features, allowing it to function both as a server and a requester for CP/M clients. Diskless client systems stored their operating system in ROM, known as CP/NOS (Network Operating System), while MP/NOS offered the MP/M environment without local disk drives, instead managing storage operations over the network.

Key components supporting this ecosystem were:

• NIOS – Network Input/Output System
• SNIOS – Slave Network Input/Output System
• NDOS – Network Disk Operating System

Versions 1.0 through 1.2 of CP/NET were designed for 8080 and Z80 CPUs, with CP/NET-86 tailored for the 8086 processor. Subsequent developments evolved into DR Net and later FlexNet.

Legacy

Starting in 1997, Caldera permitted the redistribution and modification of original Digital Research software files, including source code from the CP/M and MP/M product lines, facilitated through Tim Olmstead's "The Unofficial CP/M Web site." Following Olmstead’s death in 2001, Lineo—owner of these assets at that time—expanded the free distribution rights to encourage ongoing community engagement and the preservation of these systems.