MP/NOS
| Company type | Operating system |
|---|---|
| Industry | Computer software |
| Founded | 1979 |
| Founder | Tom Rolander |
| Products | MP/M-80, MP/M-86, MP/M-286, MP/M 8-16 |
| Parent | Digital Research |
MP/M (short for Multi-Programming Monitor Control Program) was a multi-user operating system derived from CP/M, created by Digital Research's Tom Rolander in 1979. It allowed several users to access a single machine through individual terminals.
For its era on microcomputers, MP/M was sophisticated, incorporating a priority-based multitasking kernel (referred to as the nucleus), memory protection mechanisms, simultaneous input/output management (XIOS), along with spooling and queuing capabilities. This enabled users to execute and switch among multiple applications concurrently.
MP/M-80
The 8-bit variant required an 8080 or Z80 processor and a minimum of 32 KB RAM, which constrained the memory available for programs. To overcome this limitation, MP/M utilized bank switching—loading software into RAM banks outside the CPU’s direct addressing range and swapping them into lower memory as needed. This approach was later incorporated into CP/M 3.0.
Unexpectedly, MP/M gained traction among advanced single users of CP/M due to its multitasking and expanded memory features, which justified its premium price.
MP/M II 2.0 (released in 1981) introduced file sharing capabilities, while MP/M II 2.1 (January 1982) added enhanced file locking mechanisms.
Available versions included:
- 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 extended file locking)
MP/M-86
Following the pattern of CP/M, MP/M was adapted for the 16-bit Intel 8086 processor as MP/M-86 2.0 in September 1981. Among the principal developers was Francis "Frank" R. Holsworth, who later took on a marketing director role at Digital Research. Known releases of MP/M-86 2.0 appeared in 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) to evolve into Concurrent CP/M-86 3.0 (BDOS 3.0) by late 1982, adding features such as "virtual screens". Project manager Kathryn Strutynski maintained leadership over Concurrent CP/M-86's continued development. In December 1983, an optional DOS emulator named 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), which further progressed into FlexOS and Multiuser DOS, operating systems still utilized in certain industrial environments.
The abbreviation CCP/M is commonly used for Concurrent CP/M.
MP/M 8-16
CompuPro designated MP/M 8-16 (also known as MP/M-8/16) as the integration of multi-user 16-bit MP/M-86 with single-user CP/M operations and multi-user multitasking on the 8-bit MP/M within their multi-processor hardware platform. This combined system later supported Concurrent DOS 3.1.
MP/M-286
In 1982, Digital Research announced plans for MP/M-286, aiming to exploit the Intel 80286’s advanced memory management and protection capabilities to run MP/M-86 and CP/M-86 software more effectively. Although this product never saw release in its initial form, it evolved into Concurrent CP/M-286, which served as the foundation for Concurrent DOS 286 in 1985 and subsequently FlexOS 286 in 1986.
Commands
The Console Command Processor (CCP) in MP/M II 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 designed to link an MP/M server with multiple CP/NET clients running CP/M. Created by Tom Rolander, this software facilitated shared access to files and printers as well as electronic messaging.
MP/NET expanded MP/M’s functionality by incorporating networking features that enabled it to serve both as a client requester and as a server for CP/M clients. Diskless client setups stored their operating system in ROM, identified as CP/NOS (Network Operating System), whereas MP/NOS provided MP/M without local disk storage, instead handling disk operations across the network.
The networking suite included these essential components:
- NIOS – Network Input/Output System
- SNIOS – Slave Network Input/Output System
- NDOS – Network Disk Operating System
CP/NET was released in versions 1.0 through 1.2 for 8080 and Z80 CPUs, along with CP/NET-86 for the 8086 processor. Subsequent networking solutions from Digital Research evolved into DR Net and FlexNet.
Legacy
Beginning in 1997, Caldera permitted redistribution and modification of the original CP/M and MP/M source code through Tim Olmstead’s "The Unofficial CP/M Web site." Following Olmstead’s passing in 2001, Lineo—then the rights holder—broadened the free distribution license to encourage continued community involvement and preservation efforts surrounding the CP/M software family.