PC-MOS/386 is a multi-user, multitasking

computer operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

produced by The Software Link (TSL), announced at

COMDEX COMDEX (an abbreviation of COMputer Dealers' EXhibition) was a computer expo trade show held in the Las Vegas Valley of Nevada, United States, each November from 1979 to 2003. It was one of the largest computer trade shows in the world, usually ...

in November 1986 for February 1987 release. PC-MOS/386, a successor to PC-MOS, can run many

MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few oper ...

programs on the host machine or a terminal connected to it. Unlike MS-DOS, PC-MOS/386 is optimized for the

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 transistorsx86 computer. PC-MOS/386 used to be proprietary, but it was released as

open-source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Ope ...

in 2017.

History

The last commercial version produced was v5.01, compatible with MS-DOS 5. It required a

memory management unit A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical ...

(MMU) to support memory protection, so was not compatible with

8086 The 8086 (also called iAPX 86) is a 16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released. The Intel 8088, released July 1, 1979, is a slightly modified chip with an external 8-bit data bus (allo ...

and

8088 The Intel 8088 ("''eighty-eighty-eight''", also called iAPX 88) microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 has an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and ...

processors. MMU support for 286 class machines was provided using a proprietary hardware shim inserted between the processor and its socket. 386 machines did not require any special hardware. Multi-user operation suffered from the limitations of the day including the inability of the processor to schedule and partition running processes. Typically swapping from a foreground to a background process on the same terminal used the keyboard to generate an interrupt and then swap the processes. The cost of RAM (over US$500/Mb in 1987) and the slow and expensive hard disks of the day limited performance. PC-MOS terminals could be x86 computers running

terminal emulation A terminal emulator, or terminal application, is a computer program that emulates a video terminal within some other display architecture. Though typically synonymous with a shell or text terminal, the term ''terminal'' covers all remote ter ...

software communicating at 9600 or 19200

baud In telecommunication and electronics, baud (; symbol: Bd) is a common unit of measurement of symbol rate, which is one of the components that determine the speed of communication over a data channel. It is the unit for symbol rate or modulatio ...

, connected via serial cables. However, the greatest benefit was reached when using standard, "dumb" terminals which shared the resources of the then central 386-based processor. Speeds above this required specialized hardware boards which increased cost, but the speed was not a serious limitation for interacting with text-based programs. PC-MOS also figured prominently in the lawsuit ''Arizona Retail Systems, Inc. v. The Software Link, Inc.'', where Arizona Retail Systems claimed The Software Link violated implied warranties on PC-MOS. The case is notable because The Software Link argued that it had disclaimed the implied warranties via a license agreement on the software's shrinkwrap licensing. The result of the case, which Arizona Retail Systems won, helped to establish US legal precedent regarding the enforceability of shrinkwrap licenses. There was a

year 2000 problem The year 2000 problem, also known as the Y2K problem, Y2K scare, millennium bug, Y2K bug, Y2K glitch, Y2K error, or simply Y2K refers to potential computer errors related to the formatting and storage of calendar data for dates in and after ...

-like issue in this operating system, first manifesting on 1 August 2012 rather than 1 January 2000: files created on the system from this date on would no longer work. On 21 July 2017 PCMOS/386 was relicensed under

GPL v3 The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general ...

and its

source code In computing, source code, or simply code, is any collection of code, with or without comment (computer programming), comments, written using a human-readable programming language, usually as plain text. The source code of a Computer program, p ...

uploaded to

GitHub GitHub, Inc. () is an Internet hosting service for software development and version control using Git. It provides the distributed version control of Git plus access control, bug tracking, software feature requests, task management, co ...

, with the "year 2012" issue corrected.

Commands

Commands 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 * ...

supported by PC-MOS Version 4 are:PC-MOS User Guide
/ref> * ABORT * ADDDEV * ADDTASK * ALIAS * AUTOCD * BATECHO * BREAK *

CALL Call or Calls may refer to: Arts, entertainment, and media Games * Call, a type of betting in poker * Call, in the game of contract bridge, a bid, pass, double, or redouble in the bidding stage Music and dance * Call (band), from Lahore, Pak ...

RETURN Return may refer to: In business, economics, and finance * Return on investment (ROI), the financial gain after an expense. * Rate of return, the financial term for the profit or loss derived from an investment * Tax return, a blank document o ...

* CD * CLASS * CLS *

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 ...

* COMPFILE * COPY * DATE *

DEBUG In computer programming and software development, debugging is the process of finding and resolving ''bugs'' (defects or problems that prevent correct operation) within computer programs, software, or systems. Debugging tactics can involve int ...

* DIR * DIRMAP * DISKCOPY * DISKID * DOT *

ECHO In audio signal processing and acoustics, an echo is a reflection of sound that arrives at the listener with a delay after the direct sound. The delay is directly proportional to the distance of the reflecting surface from the source and the li ...

* ED * ENVSIZE * ERASE * EXCEPT * EXPORT * FILEMODE * FLUSH *

FOR For or FOR may refer to: English language *For, a preposition *For, a complementizer *For, a grammatical conjunction Science and technology * Fornax, a constellation * for loop, a programming language statement * Frame of reference, in physic ...

FORMAT Format may refer to: Printing and visual media * Text formatting, the typesetting of text elements * Paper formats, or paper size standards * Newspaper format, the size of the paper page Computing * File format, particular way that informati ...

GOTO GoTo (goto, GOTO, GO TO or other case combinations, depending on the programming language) is a statement found in many computer programming languages. It performs a one-way transfer of control to another line of code; in contrast a function c ...

* HDSETUP * HELP * IF * IMPORT * INSERT * KEY * KEYMAP * MD * MORE * MOS * MOSADM * MSORT * MSYS * NEXT * ONLY *

PATH A path is a route for physical travel – see Trail. Path or PATH may also refer to: Physical paths of different types * Bicycle path * Bridle path, used by people on horseback * Course (navigation), the intended path of a vehicle * Desire ...

* PAUSE *

PRINT Printing is the process for reproducing text and images using a master form or template Print or printing may also refer to: Publishing * Canvas print, the result of an image printed onto canvas which is often stretched, or gallery-wrapped, o ...

PROMPT Prompt may refer to: Computing * Command prompt, characters indicating the computer is ready to accept input * Command Prompt, also known as cmd.exe or cmd, the command-line interpreter in some operating systems * Prompt (natural language), instr ...

* RD * REL *

REM Rem or REM may refer to: Music * R.E.M., an American rock band * ''R.E.M.'' (EP), by Green * "R.E.M." (song), by Ariana Grande Organizations * La République En Marche!, a French centrist political party * Reichserziehungsministerium, in Nazi G ...

* REMDEV * REMTASK *

RENAME Rename may refer to: * Rename (computing), rename of a file on a computer * RENAME (command), command to rename a file in various operating systems * Rename (relational algebra), unary operation in relational algebra * Company renaming, rename ...

* SEARCH * SET * SIGNOFF * SIGNON * SPOOL * STOP * SWITCH * TEXT * ENDTEXT *

TIME Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, t ...

TYPE Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...

VERIFY CONFIG.SYS is the primary configuration file for the DOS and OS/2 operating systems. It is a special ASCII text file that contains user-accessible setup or configuration directives evaluated by the operating system's DOS BIOS (typically residin ...

* WVER

References

{{FOSS 1987 software Discontinued operating systems Disk operating systems DOS variants Formerly proprietary software Free software operating systems Assembly language software X86 operating systems

History

Commands

See also

References