CP/NET-86
| Company type | Operating system |
|---|---|
| Industry | Software / Computer operating systems |
| Founded | 1979 |
| Founder | Tom Rolander |
| Products | MP/M-80, MP/M-86, MP/M-286, Concurrent CP/M, Concurrent DOS, FlexOS, Multiuser DOS |
| Parent | Digital Research |
MP/M (standing 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 operate a single computer through individual terminals.
For its era, MP/M was notably sophisticated, incorporating a priority-based multitasking kernel—referred to as the nucleus—with memory protection, simultaneous input/output operations (XIOS), and functionalities such as spooling and queuing. It enabled users to execute multiple applications concurrently and switch among them seamlessly.
MP/M-80
The 8-bit variant required an Intel 8080 or Zilog Z80 processor along with a minimum of 32 KB RAM, which constrained the memory available for programs. To overcome this limitation, MP/M utilized bank switching, permitting software to be loaded into RAM segments outside the CPU’s direct addressable space and swapped into lower memory as necessary—a method later adopted by CP/M version 3.0.
Unexpectedly, MP/M gained popularity as a high-end single-user system due to its multitasking abilities and expanded memory support, which justified its higher cost.
The MP/M II 2.0 release in 1981 introduced file sharing functionality, followed by MP/M II 2.1 in January 1982, which enhanced file locking mechanisms.
Release timeline:
- 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 advanced file locking)
MP/M-86
Similar to CP/M, MP/M was adapted for the 16-bit Intel 8086, debuting as MP/M-86 2.0 in September 1981. Among the principal developers was Francis "Frank" R. Holsworth, who later became a marketing director at Digital Research. Known editions of MP/M-86 2.0 were dated September and October 1981, with MP/M-86 2.1 arriving in July 1982.
The version MP/M-86 2.1 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 and adding enhancements such as "virtual screens". Project manager Kathryn Strutynski maintained her leadership role during this transition. In December 1983, an optional DOS emulator called PC-MODE was launched for Concurrent CP/M-86 3.1 (BDOS 3.1), which shipped in February 1984. This platform eventually developed into the MS-DOS compatible Concurrent DOS (BDOS versions above 3.1), which further progressed into FlexOS and Multiuser DOS, systems still operational within certain industrial sectors.
Concurrent CP/M is frequently abbreviated as CCP/M.
MP/M 8-16
The designation MP/M 8-16 (also known as MP/M-8/16) referred to CompuPro’s integration of the multi-user 16-bit MP/M-86 supporting single-user CP/M tasks alongside the multi-user, multitasking capabilities of the 8-bit MP/M on their multi-processor platform. This setup later incorporated support for Concurrent DOS 3.1.
MP/M-286
In 1982, Digital Research announced MP/M-286, intended 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 this product was never released in its original form, it evolved into Concurrent CP/M-286, which became the foundation for Concurrent DOS 286 in 1985 and subsequently FlexOS 286 in 1986.
Commands
The Console Command Processor (CCP) of MP/M II supports 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 connect an MP/M server with multiple CP/NET clients operating on CP/M, originally developed by Tom Rolander.
MP/NET enhanced MP/M by incorporating networking features that allowed it to function as both a server and requester alongside CP/M clients.
Diskless client setups, which stored their software in ROM, were marketed as CP/NOS (Network Operating System), whereas MP/NOS provided an MP/M environment without local disk storage, depending entirely on network-based disk services.
These platforms supported sharing of files and printers as well as electronic mail communication.
The principal 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 through 1.2 for 8080 and Z80 CPUs, with a version named CP/NET-86 for the 8086 processor. Subsequent developments gave rise to DR Net and FlexNet.
Legacy
Beginning in 1997, Caldera granted permission for redistribution and modification of the original Digital Research CP/M and MP/M source code via Tim Olmstead’s "The Unofficial CP/M Web site." Following Olmstead’s passing in 2001, Lineo expanded this free licensing arrangement to continue providing access to these essential operating system resources.