MP/M
| Company type | Operating system |
|---|---|
| Industry | Computer software |
| Founded | 1979 |
| Founder | Tom Rolander |
| Products | Multi-user CP/M-based operating system |
| Parent | Digital Research |
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. This system allowed several users to access a single machine through distinct terminals.
At the time, MP/M was considered sophisticated among microcomputer OSs, 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. It enabled users to execute multiple applications concurrently and switch between them seamlessly.
MP/M-80
The 8-bit variant operated on 8080 or Z80 processors and demanded a minimum of 32 KB RAM, which constrained application memory availability. To overcome this limitation, MP/M utilized bank switching—loading software into RAM segments inaccessible directly by the CPU and swapping them into lower memory as necessary. This approach was later incorporated into CP/M version 3.0.
Interestingly, MP/M gained traction among advanced single users as a more capable alternative to CP/M due to its multitasking features and larger memory support, which justified its premium cost.
MP/M II 2.0 (released in 1981) introduced file sharing capabilities, while MP/M II 2.1 (issued in January 1982) expanded functionality with enhanced file locking mechanisms.
Released versions include:
- 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; introduced extended file locking)
MP/M-86
Following the pattern of 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 served as a marketing director at Digital Research. Known iterations of MP/M-86 2.0 were dated September and October of 1981, succeeded by MP/M-86 2.1 in July 1982.
The version MP/M-86 2.1 incorporated elements from CP/M-86 1.1 (BDOS 2.2), evolving into Concurrent CP/M-86 3.0 (BDOS 3.0) by late 1982, which included new functions such as "virtual screens". Project manager Kathryn Strutynski remained responsible for ongoing development of Concurrent CP/M-86. In December 1983, an optional DOS emulator called PC-MODE was launched for Concurrent CP/M-86 3.1 (BDOS 3.1), which became available in February 1984. This platform eventually transformed into the MS-DOS compatible Concurrent DOS (BDOS versions beyond 3.1), later progressing into FlexOS and Multiuser DOS, both still operational within certain industrial sectors.
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 integrated solution combining the multi-user capabilities of the 16-bit MP/M-86 for single-user CP/M applications with multi-user multitasking on the 8-bit MP/M platform within the multi-processor CompuPro System 816 architecture. This system subsequently supported Concurrent DOS 3.1.
MP/M-286
In 1982, Digital Research announced plans for MP/M-286, designed to utilize Intel 80286 processor features such as advanced memory management and protection to run both MP/M-86 and CP/M-86 software efficiently. Although it did not launch exactly as planned, it evolved into Concurrent CP/M-286, which served as a foundation for Concurrent DOS 286 (released in 1985) and FlexOS 286 (introduced in 1986).
Commands
The Console Command Processor (CCP) in MP/M II recognizes 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 as a networking technology designed to link an MP/M server with multiple CP/NET clients operating on CP/M, a system originally developed by Tom Rolander.
MP/NET enhanced MP/M by adding network functionality, allowing it to serve as both client and server in conjunction with CP/M clients. Diskless clients ran their OS from ROM, a setup named CP/NOS (Network Operating System), while MP/NOS provided a version of MP/M without local disk hardware, relying on network-based disk services.
These solutions enabled shared access to files and printers as well as electronic mail capabilities. Associated components included:
- NIOS – Network I/O System
- SNIOS – Slave Network I/O System
- NDOS – Network Disk Operating System
Versions 1.0 through 1.2 of CP/NET were available for 8080 and Z80 processors, along with CP/NET-86 tailored for the 8086 CPU. Later developments evolved into DR Net and FlexNet.
Legacy
Starting in 1997, Caldera granted permission for redistribution and modification of all original Digital Research CP/M and MP/M files, including their source code, through Tim Olmstead's "The Unofficial CP/M Web site." Following Olmstead’s passing in 2001, Lineo—then the rights holder—broadened this free-use license later that year to encourage continued community involvement and preservation efforts.