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| Concurrent CP/M | |
|---|---|
| Name | Concurrent CP/M |
| Developer | Digital Research |
| Released | 1980 |
| Latest release | Concurrent CP/M 3.x |
| Operating system family | CP/M |
| Kernel type | Multitasking, multiuser |
| License | Proprietary |
Concurrent CP/M Concurrent CP/M was a multitasking, multiuser operating system created by Digital Research for 8-bit and later 16-bit microcomputers. It extended the CP/M family to support concurrent processes and multiple users on systems built by vendors such as Zenith Data Systems, DEC, and Ampro Computers. Designed during the transition from hobbyist microcomputers to business systems, it influenced later systems developed by companies including Microsoft and IBM.
Concurrent CP/M provided preemptive and cooperative multitasking, device independence, and layered services for application programs. It was aimed at commercial customers using hardware from Zenith Data Systems, Tandy Corporation, Sanyo, Fujitsu, and Ampro Computers and competed with systems from Microsoft and IBM. The product integrated with utilities and languages from Digital Research such as CP/M-86, WordStar, and dBase II while addressing needs also served by Xenix and UNIX-like environments.
Development began after the success of CP/M on systems like the Altair 8800 and machines sold by Heathkit and MITS. Led by engineers at Digital Research under founder Gary Kildall, work on Concurrent CP/M paralleled efforts on CP/M-86 and later projects involving GEM and DR DOS. Major milestones include adoption by OEMs such as Zenith Data Systems and ports to processors like the Intel 8086, Intel 8088, and later the Zilog Z8000. Corporate interactions involved negotiations with IBM and market pressures from Microsoft that shaped its commercial trajectory.
Concurrent CP/M implemented a modular kernel supporting process scheduling, memory management, and device drivers. It exposed APIs familiar to developers of CP/M-86, while offering extensions for multitasking and multiuser operation used in deployments alongside products like WordStar and dBase II. Features included support for terminal servers from vendors like Citrix-era concepts, file locking compatible with hardware from DEC and Digital Equipment Corporation product lines, and compatibility layers aimed at bridging software written for CP/M-86, MS-DOS, and utilities from SCO. Networking add-ons were provided by third parties supplying support for standards popularized by Novell and X/Open consortiums.
Concurrent CP/M was released for processors widely used in business microcomputers: Intel 8086, Intel 8088, Zilog Z80 (in related CP/M products), and later for architectures employed by Ampro Computers and Sanyo. OEM-specific versions appeared on machines from Zenith Data Systems, Tandy Corporation (Radio Shack TRS-80 line derivatives), Sanyo, Fujitsu, DEC, and small-business servers from Amstrad-era manufacturers. Versions were distributed alongside CP/M-86 and evolved as Digital Research engaged with OEM partners such as Heathkit and Sirius Systems Technology.
A broad software ecosystem included business applications like WordStar, dBase II, SuperCalc, and development tools such as assemblers from Digital Research and compilers for languages including BASIC, Pascal (from vendors like Borland), and Fortran used in scientific computing on machines from Fujitsu and DEC. Vertical market solutions were provided by companies that also supported CP/M, including software houses that built accounting, inventory, and point-of-sale systems for vendors like Zenith Data Systems and Tandy Corporation. Third-party utilities interfaced with office peripherals from Epson, Canon, and disk subsystems produced by Seagate and Western Digital.
Concurrent CP/M competed with contemporaries such as MS-DOS, Xenix, and UNIX System V in small business and OEM markets. Compared with MS-DOS, it offered native multitasking and multiuser capabilities similar to features later sought in DR DOS and server-oriented releases from Microsoft; against Xenix and UNIX, it targeted lower-cost microcomputer hardware from Zenith Data Systems and Tandy Corporation rather than minicomputer-class machines from DEC and Sun Microsystems. It also contrasted with the graphical ambitions of GEM and parallel efforts by Apple Computer in user interface design.
Concurrent CP/M’s innovations in multitasking and OEM partnerships influenced later operating systems and corporate strategies at companies such as Digital Research, Microsoft, and IBM. Elements of its design can be traced to multiuser and multitasking features in systems adopted by small business computing vendors, and its commercial history is tied to industry events involving IBM PC, MS-DOS licensing, and the shifting OEM market led by Zenith Data Systems and Tandy Corporation. Its influence persisted in software practices for application portability adopted by companies like Borland and in embedded and specialized systems produced by firms such as Sanyo and Fujitsu.
Category:Operating systems