FlexOS is a discontinued modular real-time multiuser multitasking operating system (

RTOS A real-time operating system (RTOS) is an operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating system ...

) designed for computer-integrated manufacturing, laboratory, retail and financial markets. Developed by

Digital Research Digital Research, Inc. (DR or DRI) was a company created by Gary Kildall to market and develop his CP/M operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides comm ...

's Flexible Automation Business Unit in Monterey, California, in 1985, the system was considered to become a successor of Digital Research's earlier

Concurrent DOS Multiuser DOS is a real-time multi-user multi-tasking operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing ...

, but with a new, modular, and considerably different system architecture and portability across several processor families. Still named Concurrent DOS 68K and Concurrent DOS 286, it was renamed into FlexOS on 1 October 1986 to better differentiate the target audiences. FlexOS was licensed by several OEMs who selected it as the basis for their own operating systems like

4680 OS FlexOS is a discontinued modular real-time multiuser multitasking operating system (RTOS A real-time operating system (RTOS) is an operating system An operating system (OS) is system software that manages computer hardware, software ...

4690 OS 4690 Operating System (sometimes shortened to 4690 OS or 4690) is a specially designed point of sale (POS) operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides comm ...

S5-DOS/MT FlexOS is a discontinued modular real-time multiuser multitasking operating system (RTOS A real-time operating system (RTOS) is an operating system An operating system (OS) is system software that manages computer hardware, software ...

and others. Unrelated to FlexOS, the original Concurrent DOS system architecture found a continuation in successors like Concurrent DOS XM and

Concurrent DOS 386 Multiuser DOS is a real-time multi-user multi-tasking operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing ...

as well.

Overview

Concurrent DOS 286, Concurrent DOS 68K and FlexOS were designed by Francis "Frank" R. Holsworth (using

siglum Scribal abbreviations or sigla ( singular: siglum) are abbreviation An abbreviation (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was or ...

FRH). Like

Portable CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/Intel 8085, 85-based microcomputers by Gary Kildall of Digital Research, Inc ...

, Concurrent DOS 286, Concurrent DOS 68K and

Concurrent DOS V60 FlexOS is a discontinued modular real-time multiuser multitasking operating system (RTOS A real-time operating system (RTOS) is an operating system An operating system (OS) is system software that manages computer hardware, software ...

, FlexOS was written in C for higher portability across hardware platforms, and it featured very low interrupt latency and fast context switching. The original

protected mode In computing, protected mode, also called protected virtual address mode, is an operational mode of x86-compatible central processing unit A central processing unit (CPU), also called a central processor, main processor or just processor, i ...

FlexOS 286 version 1.3 was designed for host machines equipped with 286 CPUs, and with adaptations for

NEC V60 is a Japanese multinational information technology Information technology (IT) is the use of computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) ...

, NEC V70 and

Motorola 68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sec ...

processors planned. FlexOS 286 executables using the system's native INT DCh ( INT 220) application program interface had the filename extension

.286 FlexOS is a discontinued modular real-time multiuser multitasking operating system (RTOS A real-time operating system (RTOS) is an operating system An operating system (OS) is system software that manages computer hardware, software ...

. A

CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system An operating system (OS) is system software that manages computer hardware, software resources, and ...

API front-end (FE) was available as well, using the extension .CMD for executables. (A filename extension of .68K was reserved for FlexOS 68K, a file extension derived from Concurrent DOS 68K as of 1986.) In May 1987, FlexOS version 1.31 was released for 80286 machines. The developer version required an IBM PC/AT-compatible machine with 640 KB of conventional and 512 KB of extended memory, and either a (monochrome) CGA or an EGA graphics adapter. FlexOS supported a concept of dynamically loadable and unloadable subdrivers, and it came with driver prototypes for floppies, hard disks, printers, serial interfaces, RAM disks, mice and console drivers. During boot, the FLEX286.SYS kernel would load the resource managers and device drivers specified in the CONFIG.SYS ''binary'' file (not to be mixed up with the similarly named CONFIG.SYS configuration file under DOS), and its shell (COMMAND.286) would execute a CONFIG.BAT startup batch job instead of the common AUTOEXEC.BAT. FlexOS's optional DOS emulator provided limited PC DOS 2.1 compatibility for DOS .COM and .EXE programs. Certain restrictions applied in " 8086 emulation mode" since these programs were executed in the processor's protected mode. Due to bugs in earlier steppings of the Intel 80286, the FlexOS 286 DOS front-end required at least the 80286 E2 stepping to function properly (see LOADALL). These problems had already caused delays in the delivery of Concurrent DOS 286 earlier. The system optionally supported a multitasking GEM VDI for graphical applications. FlexOS 1.31 could be linked with none, either or both of these two modules. FlexOS 1.31 also supported FlexNet. By June 1987 there were also versions 1.0 of FlexOS 386 (for hosts) and FlexOS 186 (for remote cell controllers). FlexOS 386 provided a windowing feature, and offered PC DOS 3.2 and GEM compatibility. FlexOS 286 and FlexOS 386 versions 2.0 were registered on 3 July 1989. Among the major FlexOS customers in 1990/1991 were

FANUC FANUC ( or ; often styled Fanuc) is a Japanese group of companies that provide automation products and services such as robotics and computer numerical control wireless systems. These companies are principally of Japan, Fanuc America Corpo ...

, IBM, ICL, Nixdorf,

Siemens Siemens AG ( ) is a German multinational conglomerate corporation and the largest industrial manufacturing company in Europe headquartered in Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city ...

, TEC, Thorn EMI Software and Micrologic.

Novell Novell, Inc. was an American software and services company headquartered in Provo, Utah Provo ( ) is the fourth-largest city in Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a ...

bought Digital Research for million in July 1991. '' X/GEM for FlexOS release 1.0'' (a.k.a. X/GEM FlexOS 286 and 386) and FlexNet were registered on 21 December 1992. FlexOS was used as the primary test platform for the new Novell Embedded Systems Technology (NEST). When Novell decided to abandon further development of the various Digital Research operating systems such as

Multiuser DOS Multiuser DOS is a real-time multi-user multi-tasking operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing ...

(a successor to Concurrent DOS) and

Novell DOS DR-DOS (written as DR DOS, without a hyphen, in versions up to and including 6.0) is a disk operating system for IBM PC compatible IBM PC compatible computers are similar to the original IBM PC, XT, and AT, all from computer giant ...

(a successor to DR DOS), they sold FlexOS off to the Santa Clara, California-based Integrated Systems Inc. (ISI) for million in July 1994. The deal comprised a direct payment of half this sum as well as shares representing 2% of the company. The company already had pSOS+, another modular real-time multitasking operating system for embedded systems, but they continued to maintain FlexOS as well. FlexOS version 2.33 was current as of May 1998 and with FlexOS 2.34 to be released soon after with added support for faster CPUs, 64 MB of memory, EIDE and ATAPI CDROM drives. Integrated Systems was bought by their competitor

Wind River Systems Wind River Systems, also known as Wind River (trademarked as Wndrvr), is an Alameda, California–based company, subsidiary of Aptiv PLC. The company develops embedded system An embedded system is a computer system—a combination of ...

in February 2000.

Commands

The following list of commands is supported by FlexOS: * ASSIGN * BACK *

BACKUP In information technology Information technology (IT) is the use of computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) automatically. Modern digita ...

* BREAK * CANCEL * CHDIR *

CHKDSK In computing, CHKDSK (short for "check disk") is a system tool and command in DOS, Digital Research Digital Research, Inc. (DR or DRI) was a company created by Gary Kildall to market and develop his CP/M operating system An operatin ...

COMMAND Command may refer to: Computing * Command (computing), a statement in a computer language * COMMAND.COM, the default operating system shell and command-line interpreter for DOS * Command key, a modifier key on Apple Macintosh computer keyboards ...

* COMP * CONFIG * COPY * CTTY * DATE * DEFINE * DIR * DISKCOMP * DISKCOPY * DISKSET * ERASE * EXIT *

FDISK In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithm In mathematics Mathematics is an area of knowledge th ...

* FIND * FORMAT * FSET * LIST * LOGOFF * LOGON * MKDIR * MORE * ORDER * PASSWORD *

PATH A path is a route for physical travel – see Trail A trail, also known as a path or track, is an unpaved lane or small road usually passing through a natural area. In the United Kingdom The United Kingdom of Great Britain and Nort ...

* PRINT * PROCESS * PROMPT * RECDIR * RECFILE * RENAME * RESTORE * RMDIR * SECURITY * SORT * SYS *

TIME Time is the continued sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of ...

TREE In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that a ...

* TYPE *

VER Ver or VER may refer to: * Voluntary Export Restraints, in international trade * VER, the IATA airport code for General Heriberto Jara International Airport * Volk's Electric Railway, Brighton, England * VerPublishing, of the German group VDM ...

* VOL

Versions

Known FlexOS versions include:

Freescale Freescale Semiconductor, Inc. was an American semiconductor A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity ...

/ NXP ColdFire MCF5251 platform: * Concurrent DOS 68K 1.0 (1985) * Concurrent DOS 68K 1.1 * Concurrent DOS 68K 1.20 (April 1986, 1986-05-27) * Concurrent DOS 68K 1.21 (1986) * FlexOS 68K 1.x?

Intel 80286 The Intel 80286 (also marketed as the iAPX 286 and often called Intel 286) is a 16-bit computing, 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non-multiplexed address bus, address ...

platform: * MP/M-286 (1982) * Concurrent CP/M-286 (1985) * Concurrent DOS 286 preview (1985-01) * Concurrent DOS 286 1.0 (1985-08-06) ** Concurrent DOS 286 1.0.01 (1985-08-18/1985-08-21) ** Concurrent DOS 286 1.0.02 (1985-08-22/1985-09-12) ** Concurrent DOS 286 1.0.03 (1985-09-10/1985-09-12) ** Concurrent DOS 286 1.0.04 (1985-09-17) ** Concurrent DOS 286 1.0.05 (1985-11-01) ** Concurrent DOS 286 1.0.06 (1985-12-10) * Concurrent DOS 286 1.1 (1986-01-07) * Concurrent DOS 286 1.2 (1986) ** Concurrent DOS 286 1.2.00 (1986-04-10/1986-04-24) ** Concurrent DOS 286 1.2.01 (1986-04-16/1986-05-19) ** Concurrent DOS 286 1.2.02 (1986-08-18) * FlexOS 286 1.3 (November 1986) * FlexOS 286 1.31 (May 1987) * FlexOS 286 1.5 (1988-02-29) * FlexOS 286 2.0.00 (1988-03-31) * FlexOS 286 2.0 (July 1989) * FlexOS 286 2.32 (July 1993)

Intel 80186 The Intel 80186, also known as the iAPX 186, or just 186, is a microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit An integrated circui ...

NEC V20 The NEC V20 is a microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit An integrated circuit or monolithic integrated circuit (also referr ...

/ V30 platform: * FlexOS 186 (1986-09-04 forked) * FlexOS 186 1.0 (June 1987)

Intel 80386 The Intel 386, originally released as 80386 and later renamed i386, is a 32-bit microprocessor introduced in 1985. The first versions had 275,000 transistors NEC V60 is a Japanese multinational information technology Information technology (IT) is the use of computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) ...

platform: *

Adaptations

IBM 4680 OS

Named IBM 4680 OS Version 1, IBM originally chose DR Concurrent DOS 286 as the basis of their ''IBM 4680'' computer for IBM Plant System products and

Point-of-Sale The point of sale (POS) or point of purchase (POP) is the time and place at which a retail transaction is completed. At the point of sale, the merchant A merchant is a person who trades in commodities produced by other people, especially ...

terminals in 1986. The last release of the IBM 4680 OS has been Version 4, before it was replaced by IBM 4690 Version 1. Versions: * IBM 4680 Operating System Version 1 Release 1 * IBM 4680 Operating System Version 1 Release 2 * IBM 4680 Operating System Version 1 Release 3 * IBM 4680 Operating System Version 2 Release 1 * IBM 4680 Operating System Version 3 Release 1 * IBM 4680 Operating System Version 4 Release 1

IBM and Toshiba 4690 OS

In July 1993, IBM announced the adoption of FlexOS version 2.32 as the basis of their IBM 4690 OS Version 1, to be pre-released on 24 September 1993 and generally made available from 25 March 1994. FlexOS 2.32 supported 286 and 386 modes, had more efficient memory management, better console and pipe systems, and brought overall quality and performance improvements compared to the version that came with IBM 4680 OS Version 4. Further, it removed limits on the number of applications running concurrently due to its more efficient use of KOSPOOL. To support

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consist ...

, IBM 4690 OS Version 2 added support for

long filename Long filename (LFN) support is Microsoft Microsoft Corporation is an American multinational corporation, multinational technology company, technology corporation producing Software, computer software, consumer electronics, personal comput ...

s by means of a virtual filesystem (VFS) architecture and it introduced

FAT32 File Allocation Table (FAT) is a file system In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithm In mathe ...

volumes. According to "The Year of the Store?", IHL Consulting Group/RIS News, IBM 4690 OS still had a market share of 12% in the POS register/client market in June 2005, when IBM was starting to phase it out in favour to

IBM Retail Environment for SUSE IBM Retail Store Solutions was IBM's division in the retail market segment. During its run, IBM Retail Store Solutions had several product lines, both hardware and software. Hardware products included IBM SurePOS 700 point-of-sale systems or pri ...

(IRES). IBM continued to maintain 4690 OS up to April 2015, with the most recent version released by IBM in May 2012 being IBM 4690 OS Version 6 Release 3. Toshiba released Toshiba 4690 OS Version 6 Release 4 in January 2014 and Version 6 Release 5 in January 2016.

Siemens S5-DOS/MT

used and still maintains FlexOS in their factory automation equipment as well. For example, their Simatic S5 STEP-5 operating system

is based on FlexOS 386 with X/GEM, FlexNet and Btrieve, whereas the smaller S5-DOS system, also present on these systems, is a variant of Digital Research's Personal CP/M-86. Siemens industrial systems like COROS LS-B/FlexOS, COROS OS-B/FlexOS, GRACIS/FlexOS, OS-525 were FlexOS and X/GEM-based. Computers such as the PC 16-20 and the PC 32 series were available with FlexOS as well.

CTM

The Japanese post office shared terminals III and CTM IV were based on FlexOS.