MP/M-80
| 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 through individual terminals.
For its era in microcomputing, MP/M was notably sophisticated, incorporating a priority-based multitasking kernel—referred to as the nucleus—along with memory protection, simultaneous input/output handling (XIOS), and capabilities for spooling and job queuing. This enabled users to execute multiple applications concurrently and switch between them seamlessly.
MP/M-80
This 8-bit platform operated on either an Intel 8080 or Zilog Z80 processor and required a minimum of 32 KB RAM, which constrained the memory available for running programs. To overcome this limitation, MP/M utilized bank switching—a method where programs were loaded into RAM banks outside the CPU’s direct addressable range and swapped into lower memory when necessary. This approach was later incorporated in CP/M version 3.0.
Unexpectedly, MP/M gained traction as a "power user" variant of CP/M targeted at individual users, offering multitasking and enhanced memory management that justified its premium pricing.
MP/M II 2.0 (released in 1981) introduced file-sharing capabilities, followed by MP/M II 2.1 (January 1982), which implemented extended 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; added extended file locking)
MP/M-86
Similar to CP/M, MP/M was adapted for the 16-bit Intel 8086 processor and appeared 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 bear dates from September and October 1981, succeeded by MP/M-86 2.1 released in July 1982.
The MP/M-86 2.1 update integrated features 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 support for multiple "virtual screens." Kathryn Strutynski, the project manager for CP/M-86, continued her leadership role overseeing Concurrent CP/M-86 development. In December 1983, an optional DOS emulator called PC-MODE was launched as part of Concurrent CP/M-86 3.1 (BDOS 3.1), shipping in February 1984. This eventually transformed into the MS-DOS compatible Concurrent DOS (BDOS version 3.1+), which further evolved into FlexOS and Multiuser DOS, still operational within certain industrial environments.
Concurrent CP/M is frequently abbreviated as CCP/M.
MP/M 8-16
The term MP/M 8-16 (also known as MP/M-8/16) referred to CompuPro’s system that merged multi-user, multi-tasking capabilities of the 8-bit MP/M with the single-user functions of the 16-bit MP/M-86 on a multi-processor architecture. This platform later supported Concurrent DOS 3.1.
MP/M-286
In 1982, Digital Research announced MP/M-286, designed to exploit Intel 80286 CPU features such as advanced memory management and protection while running both MP/M-86 and CP/M-86 software. Although this version was 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 MP/M II Console Command Processor (CCP) includes 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 system designed to link an MP/M server with multiple CP/NET clients operating CP/M, a system originally developed by Tom Rolander.
CP/NET enhanced MP/M by incorporating networking capabilities, allowing the platform to function simultaneously as a server and requester for CP/M client machines.
Diskless client setups utilized CP/NOS (Network Operating System), which stored the system software in ROM, whereas MP/NOS delivered MP/M functionality without local disk drives, depending entirely on network-based disk services.
These solutions enabled shared access to files and printers as well as electronic mail communication.
The architecture included several key components:
- 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 tailored for 8080 and Z80 processors, alongside CP/NET-86 designed for the 8086 processor.
Subsequent advancements led to the creation of DR Net and later FlexNet.
Legacy
Beginning in 1997, Caldera permitted the redistribution and modification of Digital Research’s original CP/M and MP/M software packages, including their source code, through Tim Olmstead’s "The Unofficial CP/M Web site." Following Olmstead’s death in 2001, Lineo—then holding ownership of these assets—expanded the free distribution license within that same year, ensuring continued community access and ongoing development efforts.