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Concurrent CP/M-86

From Alfawiki
MP/M
Company typeOperating system
IndustryComputer software
Founded1979
FounderTom Rolander
ProductsMP/M-80, MP/M-86, MP/M II, MP/M-286
ParentDigital 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. This system allowed several users to access a single computer simultaneously through individual terminals.

At the time, MP/M was technologically sophisticated, incorporating a priority-based multitasking kernel—referred to as the nucleus—with memory protection mechanisms, simultaneous input/output handling (XIOS), as well as spooling and queuing capabilities. It enabled users to execute multiple applications concurrently and switch between them seamlessly.

MP/M-80

Designed for 8-bit processors, MP/M-80 required an 8080 or Z80 CPU along with a minimum of 32 KB RAM, which constrained the memory available for running programs. To overcome this limitation, the system utilized bank switching—loading software into separate RAM banks beyond the CPU’s direct addressing range and swapping these banks into lower memory when necessary. This approach was subsequently incorporated into CP/M 3.0.

Interestingly, MP/M gained traction as a "power user" operating system for single users due to its multitasking functionality and enhanced memory management, justifying its premium price point.

The release MP/M II 2.0 (1981) introduced file sharing features, while MP/M II 2.1 (1982) brought in advanced file locking capabilities.

Versions released:

  • 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 and launched as MP/M-86 2.0 in September 1981. Among the 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 bear dates from September and October 1981, succeeded by MP/M-86 2.1 in July 1982.

In late 1982, MP/M-86 2.1 merged technologies from CP/M-86 1.1 (BDOS 2.2), evolving into Concurrent CP/M-86 version 3.0 (BDOS 3.0), which introduced enhancements such as "virtual screens". Kathryn Strutynski continued her project management role during this transition to Concurrent CP/M-86. An optional DOS emulator called PC-MODE was released in December 1983 as an add-on to Concurrent CP/M-86 3.1 (BDOS 3.1), which became available in February 1984. This platform eventually developed into the MS-DOS compatible Concurrent DOS (BDOS versions beyond 3.1), later evolving into FlexOS and Multiuser DOS, which remain in use within certain industrial environments.

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

MP/M 8-16

The term MP/M 8-16 (also written as MP/M-8/16) refers to CompuPro’s implementation that integrated multi-user capabilities of the 16-bit MP/M-86 with single-user CP/M functions and multi-tasking features of the 8-bit MP/M on a multi-processor platform. This configuration later supported Concurrent DOS 3.1.

MP/M-286

In 1982, Digital Research intended to develop MP/M-286 to exploit the Intel 80286 processor’s advanced memory management and protection features for both MP/M-86 and CP/M-86 applications. Although this version was not released as initially envisioned, it progressed into Concurrent CP/M-286, which served as the basis for Concurrent DOS 286 (released in 1985) and FlexOS 286 (released in 1986).

Commands

The Console Command Processor (CCP) of MP/M II accommodates 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 numerous CP/NET clients operating CP/M. Created by Tom Rolander, this software facilitated file sharing, printer access, and electronic messaging.[1][2]

MP/NET enhanced MP/M by integrating network functions, enabling it to serve as both a requester and a server for CP/M clients.[1]

Diskless client systems stored in ROM were marketed under the names CP/NOS (Network Operating System) and MP/NOS. These systems operated without local disk drives, depending entirely on networked disk resources.[1]

The supporting modules comprised:

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

CP/NET was issued in versions 1.0, 1.1, and 1.2 for 8080 and Z80 processors, along with CP/NET-86 tailored for the 8086 processor. Subsequent developments included DR Net and FlexNet.

Legacy

Starting in 1997, Caldera granted permission for redistribution and modification of original Digital Research materials—including source code—related to the CP/M and MP/M product lines through Tim Olmstead's "The Unofficial CP/M Web site." Following Olmstead's passing in 2001, Lineo, which acquired these assets, further broadened this free licensing arrangement.[3][4][5]

Notes

  1. ↑ 1.0 1.1 1.2 Cite error: Invalid <ref> tag; no text was provided for refs named Kildall_1981_CP/M
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named IEEE_2014
  3. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Olmstead_1997_1
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Caldera_1997_CP/M
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Sparks_2001_CP/M
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