MP/NET
| Company type | Software |
|---|---|
| Industry | Computer software |
| Founded | 1979 |
| Founder | Tom Rolander |
| Products | MP/M operating system |
MP/M (Multi-Programming Monitor Control Program) was a multi-user iteration of the CP/M operating system developed by Digital Research's Tom Rolander in 1979, now discontinued. It allowed several users to access a single machine through distinct terminals.
For its era on microcomputers, MP/M was sophisticated, incorporating a priority-based multitasking kernel—then referred to as the nucleus—with memory protection, simultaneous input/output (XIOS), and capabilities for spooling and queuing. Users could execute multiple applications concurrently and switch among them.
MP/M-80
This 8-bit version required an 8080 or Z80 processor along with at least 32 KB of RAM, which constrained the memory accessible for programs. To overcome this limitation, MP/M implemented bank switching—loading software into RAM banks beyond the CPU’s directly addressable memory space, which could then be swapped into low memory when necessary. This approach was later incorporated into CP/M version 3.0.
Unexpectedly, MP/M attracted a user base among "power users" operating single-user systems due to its multitasking and enhanced memory management features, justifying its premium price.
The release of MP/M II 2.0 in 1981 introduced file sharing capabilities, followed by MP/M II 2.1 in January 1982, which added advanced file locking mechanisms.
Versions released 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
Similar to 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 became a marketing director at Digital Research. Known versions of MP/M-86 2.0 bear dates from September and October 1981, with MP/M-86 2.1 arriving in July 1982.
The MP/M-86 2.1 update incorporated elements from CP/M-86 1.1 (BDOS 2.2) to create Concurrent CP/M-86 version 3.0 (BDOS 3.0) by late 1982, adding features such as "virtual screens". Kathryn Strutynski continued her role as project manager for Concurrent CP/M-86. In December 1983, an optional DOS emulator called PC-MODE was introduced as part of Concurrent CP/M-86 3.1 (BDOS 3.1), released in February 1984. This platform evolved into the MS-DOS compatible Concurrent DOS (BDOS version 3.1+), which further progressed into FlexOS and Multiuser DOS, still utilized in certain industrial environments.
The term CCP/M is commonly used as an abbreviation for Concurrent CP/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 multi-user, multitasking 8-bit MP/M running on a multi-processor system alongside single-user CP/M tasks managed by the 16-bit MP/M-86 platform. This setup later supported Concurrent DOS 3.1.
MP/M-286
In 1982, Digital Research announced MP/M-286, designed to exploit the Intel 80286 processor’s advanced memory management and protection features to execute MP/M-86 and CP/M-86 programs. Although the initially announced MP/M-286 did not reach release as planned, it evolved into Concurrent CP/M-286, which served as a foundation for Concurrent DOS 286 (1985) and FlexOS 286 (1986).
Commands
The Console Command Processor (CCP) for MP/M II supports a variety of commands, including:
- 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
In the early 1980s, Digital Research introduced CP/NET, a networking software designed to link an MP/M server with several CP/NET clients operating under CP/M. Created by Tom Rolander, CP/NET facilitated shared access to files and printers as well as electronic messaging.
Building upon this, MP/NET expanded MP/M’s functionality by incorporating networking features that allowed it to act both as a server and a requester in conjunction with CP/M clients.
Systems without local disk drives, storing their operating system in ROM, were designated as CP/NOS (Network Operating System). Similarly, MP/NOS provided MP/M without local disk support, relying on network-based disk operations.
Key supporting modules included:
- NIOS – Network I/O System
- SNIOS – Slave Network I/O System
- NDOS – Network Disk Operating System
CP/NET was released in versions 1.0 through 1.2 for 8080 and Z80 CPUs, alongside CP/NET-86 tailored for 8086 processors.
Subsequent networking products evolved into DR Net and later FlexNet.
Legacy
Beginning in 1997, Caldera granted permission for redistribution and modification of original Digital Research software components, including source code for both the CP/M and MP/M families. This initiative was hosted by Tim Olmstead’s "The Unofficial CP/M Web site." After Olmstead passed away in 2001, the license was renewed and expanded under the stewardship of Lineo, which then held the Digital Research intellectual property rights.