Concurrent CP/M-68K
| Company type | Software |
|---|---|
| Industry | Computer software |
| Founded | 1979 |
| Founder | Tom Rolander |
| Products | Multi-user adaptation of CP/M operating system |
MP/M (standing for Multi-Programming Monitor Control Program) was a multi-user adaptation of the CP/M operating system, created by Digital Research's Tom Rolander in 1979. This system allowed several users to access a single computer simultaneously through individual terminals.
At the time, MP/M was a sophisticated solution for microcomputers, incorporating a priority-based multitasking kernel (referred to as the nucleus) with features such as memory protection, concurrent input/output (XIOS), and mechanisms for spooling and queuing. It enabled users to execute multiple applications concurrently and switch between them seamlessly.
MP/M-80
The 8-bit variant operated on an Intel 8080 or Zilog Z80 processor and required a minimum of 32 KB RAM, which constrained the memory accessible to programs. To overcome this limitation, MP/M employed bank switching to map different memory banks into the CPU's address space, permitting larger software to run—this approach was later adopted in CP/M version 3.0.
Interestingly, MP/M also gained traction among advanced single users who valued its multitasking capabilities and extended memory support despite its premium price.
The release of MP/M II 2.0 in 1981 brought file sharing functions, followed by MP/M II 2.1 in January 1982, which introduced enhanced file locking.
Notable releases include:
- 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
Mirroring CP/M’s evolution, MP/M was adapted for the 16-bit Intel 8086, debuting as MP/M-86 2.0 in September 1981. Among its principal contributors was Francis "Frank" R. Holsworth, who later assumed a marketing director role at Digital Research. Known versions of MP/M-86 2.0 appeared in September and October of 1981, with MP/M-86 2.1 following in July 1982.
The version 2.1 incorporated elements from CP/M-86 1.1 (BDOS 2.2), transforming into Concurrent CP/M-86 3.0 (BDOS 3.0) by late 1982 and adding support for "virtual screens." Project manager Kathryn Strutynski remained at the helm of Concurrent CP/M-86’s ongoing development. In December 1983, the DOS emulator PC-MODE was launched as an optional add-on for Concurrent CP/M-86 3.1 (BDOS 3.1), which shipped in February 1984. This platform eventually evolved into the MS-DOS compatible Concurrent DOS (BDOS versions beyond 3.1), which further progressed into FlexOS and Multiuser DOS, systems still utilized within certain industrial environments.
Concurrent CP/M is commonly abbreviated as CCP/M.
MP/M 8-16
MP/M 8-16 (also known as MP/M-8/16) was CompuPro’s designation for a hybrid configuration that combined the multi-user capabilities of the 16-bit MP/M-86 with single-user CP/M functions alongside multi-user, multitasking operations from the 8-bit MP/M on a multi-processor platform. This architecture later supported running Concurrent DOS 3.1.
MP/M-286
Announced in 1982 by Digital Research, MP/M-286 aimed to exploit the Intel 80286 processor’s advanced memory management and protection features to run both MP/M-86 and CP/M-86 software. Although it never reached the market as initially envisioned, it evolved into Concurrent CP/M-286, which subsequently served as the foundation for Concurrent DOS 286 (released in 1985) and FlexOS 286 (released in 1986).
Commands
The Console Command Processor (CCP) within MP/M II recognizes and executes 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
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 under CP/M, originally developed by Tom Rolander.
CP/NET expanded MP/M capabilities by supporting both client requester and server functionalities for CP/M machines. Diskless client variants stored their operating system in ROM, referred to as CP/NOS (Network Operating System). Meanwhile, MP/NOS provided an MP/M environment without local disk drives, managing disk operations remotely via the network.
These platforms enabled shared access to files and printers as well as electronic mail communication.
Associated elements 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, 1.1, and 1.2 targeting 8080 and Z80 processors, along with CP/NET-86 tailored for the 8086 architecture. Subsequent iterations evolved into DR Net and FlexNet.
Legacy
Starting in 1997, Caldera permitted the redistribution and modification of Digital Research’s 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 this free licensing arrangement to encourage continued community-driven development and preservation efforts.