MP/M-86

MP/M
Company type	Operating system
Industry	Computer software
Founded	1979
Founder	Tom Rolander
Products	MP/M-80, MP/M II, MP/M-86, MP/M 8-16, MP/M-286
Parent	Digital Research

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

At the time, MP/M represented a significant advancement for microcomputers, featuring a multitasking kernel managed by priority scheduling (referred to as the nucleus), memory protection, simultaneous input/output operations (XIOS), and capabilities for spooling and queue management. This enabled users to execute multiple applications concurrently and switch between them seamlessly.

MP/M-80

This 8-bit system required an 8080 or Z80 processor along with a minimum of 32 KB RAM, which limited available memory for programs. To address this constraint, MP/M employed bank switching—loading software into RAM banks beyond the CPU's direct address space and swapping them into lower memory as necessary. This method was later incorporated into CP/M version 3.0.

Unexpectedly, MP/M also gained traction as a single-user operating system favored by "power users" due to its multitasking abilities and expanded memory management, justifying its premium price.

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

Release timeline:

MP/M 1.0 (1979)
MP/M 1.1 (January 1980)
MP/M II 2.0 (July 1981; introduced file sharing)
MP/M II 2.1 (January 1982; added advanced 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. Key contributors included Francis "Frank" R. Holsworth, who later became a marketing director at Digital Research. Known versions of MP/M-86 2.0 were released in September and October 1981, followed by MP/M-86 2.1 in July 1982.

The release of MP/M-86 2.1 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, which added features such as "virtual screens." Kathryn Strutynski managed both CP/M-86 and Concurrent CP/M-86 projects. In December 1983, an optional DOS emulator named PC-MODE was launched for Concurrent CP/M-86 3.1 (BDOS 3.1), shipping in February 1984. This system eventually developed into the MS-DOS compatible Concurrent DOS (BDOS version 3.1+), which later evolved into FlexOS and Multiuser DOS, still utilized in certain industrial environments.

The abbreviation CCP/M is commonly used for Concurrent CP/M.

MP/M 8-16

MP/M 8-16 (also known as MP/M-8/16) was CompuPro's designation for a hybrid platform combining the multi-user capabilities of the 16-bit MP/M-86 for single-user CP/M operations with the multi-user, multitasking features of the 8-bit MP/M on the multi-processor CompuPro System 816 hardware. This system subsequently supported running Concurrent DOS 3.1.

MP/M-286

In 1982, Digital Research announced MP/M-286, designed to exploit the Intel 80286 processor’s advanced memory management and protection features for applications originally targeting MP/M-86 and CP/M-86. Although it never launched as initially intended, it evolved into Concurrent CP/M-286, which served as the foundation for Concurrent DOS 286 (1985) and FlexOS 286 (1986).

Commands

The Console Command Processor (CCP) of MP/M II offers support for the following 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

Networking Solutions: CP/NET, CP/NOS, MP/NET, and MP/NOS

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

Building on this foundation, MP/NET enhanced MP/M by incorporating networking features that allowed it to function both as a client and a server in conjunction with CP/M workstations. Diskless client setups stored their operating system in ROM under the designation CP/NOS (Network Operating System), while MP/NOS offered equivalent diskless operation for MP/M systems, handling disk services over the network.

Supporting components encompassed:

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

CP/NET was released in versions 1.0 through 1.2 targeting 8080 and Z80 processors, with CP/NET-86 designed for the 8086 architecture. Subsequent developments led to products like DR Net and FlexNet.

Legacy

Starting in 1997, Caldera permitted the redistribution and modification of original Digital Research CP/M and MP/M software files, including their source code, through Tim Olmstead’s "The Unofficial CP/M Web site." Following Olmstead’s death in 2001, Lineo—then the rights holder—broadened the free distribution license to encourage continued community engagement and preservation initiatives.

References