MP/M-286

MP/M

Company type	Operating system
Industry	Computer software
Founded	1979
Founder	Tom Rolander
Products	MP/M (Multi-Programming Monitor Control Program)

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 simultaneously through distinct terminals.

At the time, MP/M was considered sophisticated for microcomputer environments, featuring a priority-based multitasking kernel—referred to as the nucleus—along with memory protection, simultaneous input/output operations (XIOS), and capabilities for spooling and queue management. Users could run multiple applications concurrently and switch between them seamlessly.

MP/M-80

This 8-bit variant required an Intel 8080 or Zilog Z80 processor and a minimum of 32 KB RAM, which constrained the memory available for programs. To overcome this limitation, MP/M implemented bank switching, enabling programs to reside in otherwise inaccessible RAM banks and be swapped into lower memory as necessary. This approach was later incorporated into CP/M version 3.0.

Interestingly, MP/M gained traction as a preferred "power user" single-user upgrade over CP/M due to its multitasking functionality and extended memory support, justifying its premium cost.

MP/M II 2.0 (1981) introduced shared file access, while MP/M II 2.1 (January 1982) enhanced the system with advanced file locking mechanisms.

Release timeline:

• 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; extended file locking)

MP/M-86

Mirroring CP/M's evolution, MP/M was ported to the 16-bit Intel 8086 processor, debuting as MP/M-86 2.0 in September 1981. Among the principal contributors was Francis "Frank" R. Holsworth, who later served as a marketing director at Digital Research. Known versions of MP/M-86 2.0 carry September and October 1981 dates, followed by MP/M-86 2.1 in July 1982.

The release of MP/M-86 2.1 incorporated technology from CP/M-86 1.1 (BDOS 2.2), evolving into Concurrent CP/M-86 version 3.0 (BDOS 3.0) by late 1982, which introduced features such as "virtual screens." Kathryn Strutynski managed the project throughout Concurrent CP/M-86’s development. In December 1983, the DOS emulator PC-MODE became available as an optional add-on for Concurrent CP/M-86 version 3.1 (BDOS 3.1), which shipped in February 1984. This platform eventually transitioned into the MS-DOS-compatible Concurrent DOS (BDOS versions above 3.1), which further evolved into FlexOS and Multiuser DOS, systems still operational in certain industrial applications.

Concurrent CP/M is often abbreviated as CCP/M.

MP/M 8-16

The term MP/M 8-16 (also known as MP/M-8/16) was used by CompuPro to describe a hybrid system that combined multi-user capabilities of the 16-bit MP/M-86 for single-user CP/M tasks with multi-user, multitasking functions of the 8-bit MP/M on their multi-processor CompuPro System 816 hardware platform. This configuration later supported Concurrent DOS 3.1.

MP/M-286

Announced in 1982 by Digital Research, MP/M-286 was intended to take advantage of the Intel 80286 processor’s enhanced memory management and protection features for executing MP/M-86 and CP/M-86 software. Although it never appeared in its initial form, it eventually transformed into Concurrent CP/M-286, which served as the basis for Concurrent DOS 286 released in 1985 and FlexOS 286 launched in 1986.

Commands

The Console Command Processor (CCP) of MP/M II provides support for 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 designed to link an MP/M server with multiple CP/NET clients operating on CP/M. Developed initially by Tom Rolander, CP/NET facilitated the sharing of files and printers across networks as well as electronic mail communication.

MP/NET expanded upon MP/M's capabilities by functioning simultaneously as a requester and server for CP/M clients. Diskless client setups utilized CP/NOS (Network Operating System), which stored the system in ROM. In a similar manner, MP/NOS operated MP/M without local disk drives, relying on network access for disk operations.

Key supporting modules included:

• NIOS – Network I/O System
• SNIOS – Slave Network I/O System
• NDOS – Network Disk Operating System

CP/NET was distributed in versions 1.0 through 1.2 for 8080 and Z80 microprocessors, with an additional CP/NET-86 variant tailored for the 8086 processor. Subsequent networking products from Digital Research evolved into DR Net and FlexNet.

Legacy

Beginning in 1997, Caldera granted permission for redistribution and modification of all original Digital Research CP/M and MP/M software components, including their source code, through Tim Olmstead's "The Unofficial CP/M Web site." Following Olmstead’s passing in 2001, Lineo—then the proprietor of Digital Research's intellectual property—broadened this free licensing arrangement to maintain continued public availability of these foundational operating systems.