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operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...
s (OSes) provide a set of functions needed and used by most application programs on a computer, and the links needed to control and synchronize computer hardware. On the first computers, with no operating system, every program needed the full hardware specification to run correctly and perform standard tasks, and its own drivers for
peripheral A peripheral device, or simply peripheral, is an auxiliary hardware device that a computer uses to transfer information externally. A peripheral is a hardware component that is accessible to and controlled by a computer but is not a core compo ...
devices like printers and punched paper card readers. The growing complexity of hardware and application programs eventually made operating systems a necessity for everyday use.


Background

Early computers lacked any form of operating system. Instead, the user, also called the operator, had sole use of the machine for a scheduled period of time. The operator would arrive at the computer with program and data which needed to be loaded into the machine before the program could be run. Loading of program and data was accomplished in various ways including toggle switches, punched paper cards and magnetic or paper tape. Once loaded, the machine would be set to execute the single program until that program completed or crashed. Programs could generally be debugged via a control panel using dials, toggle switches and panel lights, making it a very manual and error-prone process. Symbolic languages,
assemblers Assembler may refer to: Arts and media * Nobukazu Takemura, avant-garde electronic musician, stage name Assembler * Assemblers, a fictional race in the ''Star Wars'' universe * Assemblers, an alternative name of the superhero group Champions of ...
,
compiler In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...
s were developed for programmers to translate symbolic program code into
machine code In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binaryOn nonb ...
that previously would have been hand-encoded. Later machines came with
libraries A library is a collection of Book, books, and possibly other Document, materials and Media (communication), media, that is accessible for use by its members and members of allied institutions. Libraries provide physical (hard copies) or electron ...
of support code on punched cards or magnetic tape, which would be linked to the user's program to assist in operations such as input and output. This was the genesis of the modern-day operating system; however, machines still ran a single program or job at a time. At
Cambridge University The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...
in England the
job queue In system software, a job queue ( batch queue, input queue), is a data structure maintained by job scheduler software containing jobs to run. Users submit their programs that they want executed, "jobs", to the queue for batch processing. The ...
was at one time a string from which tapes attached to corresponding job tickets were hung with stationery pegs. As machines became more powerful the time to run programs diminished, and the time to hand off the equipment to the next user became large by comparison. Accounting for and paying for machine usage moved on from checking the wall clock to automatic logging by the computer. Run queues evolved from a literal queue of people at the door, to a heap of media on a jobs-waiting table, or batches of punched cards stacked one on top of the other in the reader, until the machine itself was able to select and sequence which
magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic ...
drives processed which tapes. Where program developers had originally had access to run their own jobs on the machine, they were supplanted by dedicated machine operators who looked after the machine and were less and less concerned with implementing tasks manually. When commercially available computer centers were faced with the implications of data lost through tampering or operational errors, equipment vendors were put under pressure to enhance the runtime libraries to prevent misuse of system resources. Automated monitoring was needed not just for CPU usage but for counting pages printed, cards punched, cards read, disk storage used and for signaling when operator intervention was required by jobs such as changing magnetic tapes and paper forms. Security features were added to operating systems to record
audit trail An audit trail (also called audit log) is a security-relevant chronological record, set of records, and/or destination and source of records that provide documentary evidence of the sequence of activities that have affected at any time a specific ...
s of which programs were accessing which files and to prevent access to a production payroll file by an engineering program, for example. All these features were building up towards the repertoire of a fully capable operating system. Eventually the runtime libraries became an amalgamated program that was started before the first customer job and could read in the customer job, control its execution, record its usage, reassign hardware resources after the job ended, and immediately go on to process the next job. These resident background programs, capable of managing multi step processes, were often called
monitor Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, Wes ...
s or monitor-programs before the term "operating system" established itself. An underlying program offering basic hardware management, software scheduling and resource monitoring may seem a remote ancestor to the user-oriented OSes of the
personal computing A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as word processing, internet browsing, email, multimedia playback, and gaming. Personal computers ar ...
era. But there has been a shift in the meaning of OS. Just as early automobiles lacked speedometers, radios, and air conditioners which later became standard, more and more optional software features became standard in every OS package. This has led to the perception of an OS as a complete user system with an integrated
graphical user interface A graphical user interface, or GUI, is a form of user interface that allows user (computing), users to human–computer interaction, interact with electronic devices through Graphics, graphical icon (computing), icons and visual indicators such ...
, utilities, and some applications such as
file manager A file manager or file browser is a computer program that provides a user interface to manage computer files, files and folder (computing), folders. The most common Computer file#Operations, operations performed on files or groups of files incl ...
s,
text editor A text editor is a type of computer program that edits plain text. An example of such program is "notepad" software (e.g. Windows Notepad). Text editors are provided with operating systems and software development packages, and can be used to c ...
s, and configuration tools. The true descendant of the early operating systems is what is now called the " kernel". In technical and development circles the old restricted sense of an OS persists because of the continued active development of embedded operating systems for all kinds of devices with a data-processing component, from hand-held gadgets up to industrial robots and real-time control systems, which do not run user applications at the front end. An embedded OS in a device today is not so far removed as one might think from its ancestor of the 1950s. The broader categories of systems and application software are discussed in the
computer software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...
article.


Mainframes

The first operating system used for real work was GM-NAA I/O, produced in 1956 by
General Motors General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...
' Research division for its
IBM 704 The IBM 704 is the model name of a large digital computer, digital mainframe computer introduced by IBM in 1954. Designed by John Backus and Gene Amdahl, it was the first mass-produced computer with hardware for floating-point arithmetic. The I ...
. Most other early operating systems for IBM mainframes were also produced by customers. Early operating systems were very diverse, with each vendor or customer producing one or more operating systems specific to their particular
mainframe computer A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterprise ...
. Every operating system, even from the same vendor, could have radically different models of commands, operating procedures, and such facilities as debugging aids. Typically, each time the manufacturer brought out a new machine, there would be a new operating system, and most applications would have to be manually adjusted, recompiled, and retested.


Systems on IBM hardware

The state of affairs continued until the 1960s when
IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
, already a leading hardware vendor, stopped work on existing systems and put all its effort into developing the
System/360 The IBM System/360 (S/360) is a family of mainframe computer systems announced by IBM on April 7, 1964, and delivered between 1965 and 1978. System/360 was the first family of computers designed to cover both commercial and scientific applicati ...
series of machines, all of which used the ''same'' instruction and input/output architecture. IBM intended to develop a single operating system for the new hardware, the
OS/360 OS/360, officially known as IBM System/360 Operating System, is a discontinued batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964; it was influenced by the earlier IBSYS/IBJOB a ...
. The problems encountered in the development of the OS/360 are legendary, and are described by
Fred Brooks Frederick Phillips Brooks Jr. (April 19, 1931 – November 17, 2022) was an American computer architect, software engineer, and computer scientist, best known for managing development of IBM's System/360 family of mainframe computers and the ...
in ''
The Mythical Man-Month ''The Mythical Man-Month: Essays on Software Engineering'' is a book on software engineering and project management by Fred Brooks first published in 1975, with subsequent editions in 1982 and 1995. Its central theme is that adding manpower to a s ...
''—a book that has become a classic of
software engineering Software engineering is a branch of both computer science and engineering focused on designing, developing, testing, and maintaining Application software, software applications. It involves applying engineering design process, engineering principl ...
. Because of performance differences across the hardware range and delays with software development, a whole family of operating systems was introduced instead of a single OS/360. IBM wound up releasing a series of stop-gaps followed by two longer-lived operating systems: *
OS/360 OS/360, officially known as IBM System/360 Operating System, is a discontinued batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964; it was influenced by the earlier IBSYS/IBJOB a ...
for mid-range and large systems. This was available in three
system generation In computing system generation or sysgen is the process of creating a particular unique instance of an operating system by combining user-specified options and parameters with manufacturer-supplied general-purpose program code to produce an opera ...
options: ** PCP for early users and for those without the resources for multiprogramming. ** MFT for mid-range systems, replaced by MFT-II in OS/360 Release 15/16. This had one successor, OS/VS1, which was discontinued in the 1980s. ** MVT for large systems. This was similar in most ways to PCP and MFT (most programs could be ported among the three without being re-compiled), but has more sophisticated memory management and a
time-sharing In computing, time-sharing is the Concurrency (computer science), concurrent sharing of a computing resource among many tasks or users by giving each Process (computing), task or User (computing), user a small slice of CPU time, processing time. ...
facility, TSO. MVT had several successors including the current
z/OS z/OS is a 64-bit operating system for IBM z/Architecture mainframes, introduced by IBM in October 2000. It derives from and is the successor to OS/390, which in turn was preceded by a string of MVS versions.Starting with the earliest: ...
. *
DOS/360 Disk Operating System/360, also DOS/360, or simply DOS, is the discontinued first member of a sequence of operating systems for IBM System/360, System/370 and later mainframes. It was announced by IBM on the last day of 1964, and it was first d ...
for small System/360 models had several successors including the current z/VSE. It was significantly different from OS/360. IBM maintained full compatibility with the past, so that programs developed in the sixties can still run under z/VSE (if developed for DOS/360) or z/OS (if developed for MFT or MVT) with no change. IBM also developed TSS/360, a time-sharing system for the System/360 Model 67. Overcompensating for their perceived importance of developing a timeshare system, they set hundreds of developers to work on the project. Early releases of TSS were slow and unreliable; by the time TSS had acceptable performance and reliability, IBM wanted its TSS users to migrate to OS/360 and OS/VS2; while IBM offered a TSS/370 PRPQ, they dropped it after 3 releases. Several operating systems for the IBM S/360 and S/370 architectures were developed by third parties, including the
Michigan Terminal System The Michigan Terminal System (MTS) is one of the first time-sharing computer operating systems.. Created in 1967 at the University of Michigan for use on IBM System/360, IBM S/360-67, S/370 and compatible mainframe computers, it was developed and ...
(MTS) and MUSIC/SP.


Other mainframe operating systems

Control Data Corporation Control Data Corporation (CDC) was a mainframe and supercomputer company that in the 1960s was one of the nine major U.S. computer companies, which group included IBM, the Burroughs Corporation, and the Digital Equipment Corporation (DEC), the N ...
developed the SCOPE operating systemsCDC used the SCOPE name for disparate operating systems on the upper 3000 series, the lower 3000 series, the 6000 series and the 7600 in the 1960s, for
batch processing Computerized batch processing is a method of running software programs called jobs in batches automatically. While users are required to submit the jobs, no other interaction by the user is required to process the batch. Batches may automatically ...
and later developed the MACE operating system for time sharing, which was the basis for the later Kronos. In cooperation with the
University of Minnesota The University of Minnesota Twin Cities (historically known as University of Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Twin Cities of Minneapolis and Saint ...
, the Kronos and later the NOS operating systems were developed during the 1970s, which supported simultaneous batch and time sharing use. Like many commercial time sharing systems, its interface was an extension of the DTSS time sharing system, one of the pioneering efforts in timesharing and programming languages. In the late 1970s, Control Data and the
University of Illinois The University of Illinois Urbana-Champaign (UIUC, U of I, Illinois, or University of Illinois) is a public university, public land-grant university, land-grant research university in the Champaign–Urbana metropolitan area, Illinois, United ...
developed the
PLATO system PLATO (Programmed Logic for Automatic Teaching Operations), also known as Project Plato and Project PLATO, was the first generalized computer-assisted instruction system. Starting in 1960, it ran on the University of Illinois's ILLIAC I compu ...
, which used plasma panel displays and long-distance time sharing networks. PLATO was remarkably innovative for its time; the shared memory model of PLATO's TUTOR programming language allowed applications such as real-time chat and multi-user graphical games. For the
UNIVAC 1107 The UNIVAC 1100/2200 series is a series of compatible 36-bit computer systems, beginning with the UNIVAC 1107 in 1962, initially made by Sperry Rand. The series continues to be supported today by Unisys Corporation as the ClearPath Dorado Serie ...
,
UNIVAC UNIVAC (Universal Automatic Computer) was a line of electronic digital stored-program computers starting with the products of the Eckert–Mauchly Computer Corporation. Later the name was applied to a division of the Remington Rand company and ...
, the first commercial computer manufacturer, produced the EXEC I operating system, and
Computer Sciences Corporation Computer Sciences Corporation (CSC) was an American multinational corporation that provided information technology (IT) services and professional services. On April 3, 2017, it merged with the Enterprise Services line of business of HP Ente ...
developed the EXEC II operating system and delivered it to UNIVAC. EXEC II was ported to the
UNIVAC 1108 The UNIVAC 1100/2200 series is a series of compatible 36-bit computer systems, beginning with the UNIVAC 1107 in 1962, initially made by Sperry Rand. The series continues to be supported today by Unisys Corporation as the ClearPath Dorado Series ...
. Later, UNIVAC developed the EXEC 8 operating system for the 1108; it was the basis for operating systems for later members of the family. Like all early mainframe systems, EXEC I and EXEC II were a batch-oriented system that managed magnetic drums, disks, card readers and line printers; EXEC 8 supported both batch processing and on-line transaction processing. In the 1970s, UNIVAC produced the Real-Time Basic (RTB) system to support large-scale time sharing, also patterned after the
Dartmouth BASIC Dartmouth BASIC is the original version of the BASIC programming language. It was designed by two professors at Dartmouth College, John G. Kemeny and Thomas E. Kurtz. With the underlying Dartmouth Time-Sharing System (DTSS), it offered an interac ...
system.
Burroughs Corporation The Burroughs Corporation was a major American manufacturer of business equipment. The company was founded in 1886 as the American Arithmometer Company by William Seward Burroughs I, William Seward Burroughs. The company's history paralleled many ...
introduced the
B5000 The Burroughs Large Systems Group produced a family of large 48-bit mainframes using stack machine instruction sets with dense syllables.E.g., 12-bit syllables for B5000, 8-bit syllables for B6500 The first machine in the family was the B5000 i ...
in 1961 with the MCP ( Master Control Program) operating system. The B5000 was a stack machine designed to exclusively support high-level languages, with no software, not even at the lowest level of the operating system, being written directly in
machine language In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binaryOn nonb ...
or
assembly language In computing, assembly language (alternatively assembler language or symbolic machine code), often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence bet ...
; the MCP was the first OS to be written entirely in a high-level language - ESPOL, a dialect of
ALGOL 60 ALGOL 60 (short for ''Algorithmic Language 1960'') is a member of the ALGOL family of computer programming languages. It followed on from ALGOL 58 which had introduced code blocks and the begin and end pairs for delimiting them, representing a ...
- although ESPOL had specialized statements for each "syllable"A syllable in the B5000 could contain a 10-bit literal, an
operand In mathematics, an operand is the object of a mathematical operation, i.e., it is the object or quantity that is operated on. Unknown operands in equalities of expressions can be found by equation solving. Example The following arithmetic expres ...
call, a descriptor call or a 10-bit
opcode In computing, an opcode (abbreviated from operation code) is an enumerated value that specifies the operation to be performed. Opcodes are employed in hardware devices such as arithmetic logic units (ALUs), central processing units (CPUs), and ...
.
in the B5000 instruction set. MCP also introduced many other ground-breaking innovations, such as being one ofThe B5000 was contemporaneous with the
Ferranti Ferranti International PLC or simply Ferranti was a UK-based electrical engineering and equipment firm that operated for over a century, from 1885 until its bankruptcy in 1993. At its peak, Ferranti was a significant player in power grid system ...
Atlas An atlas is a collection of maps; it is typically a bundle of world map, maps of Earth or of a continent or region of Earth. Advances in astronomy have also resulted in atlases of the celestial sphere or of other planets. Atlases have traditio ...
the first commercial implementations of
virtual memory In computing, virtual memory, or virtual storage, is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a ver ...
. The rewrite of MCP for the B6500 is now marketed as the
Unisys Unisys Corporation is a global technology solutions company founded in 1986 and headquartered in Blue Bell, Pennsylvania. The company provides cloud, AI, digital workplace, logistics, and enterprise computing services. History Founding Unis ...
ClearPath/MCP. GE introduced the
GE-600 series The GE-600 series is a family of 36-bit Mainframe computer, mainframe computers originating in the 1960s, built by General Electric (GE). When GE left the mainframe business, the line was sold to Honeywell, which built similar systems into the 1 ...
with the General Electric Comprehensive Operating Supervisor (GECOS) operating system in 1962. After
Honeywell Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building automation, industrial automa ...
acquired GE's computer business, it was renamed to General Comprehensive Operating System (GCOS). Honeywell expanded the use of the GCOS name to cover all its operating systems in the 1970s, though many of its computers had nothing in common with the earlier GE 600 series and their operating systems were not derived from the original GECOS.
Project MAC Computer Science and Artificial Intelligence Laboratory (CSAIL) is a research institute at the Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in ...
at MIT, working with GE and
Bell Labs Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...
, developed
Multics Multics ("MULTiplexed Information and Computing Service") is an influential early time-sharing operating system based on the concept of a single-level memory.Dennis M. Ritchie, "The Evolution of the Unix Time-sharing System", Communications of t ...
, which introduced the concept of ringed security privilege levels.
Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until ...
developed
TOPS-10 TOPS-10 System (Timesharing / Total Operating System-10) is a discontinued operating system from Digital Equipment Corporation (DEC) for the PDP-10 (or DECsystem-10) mainframe computer family. Launched in 1967, TOPS-10 evolved from the earlier "Mo ...
for its
PDP-10 Digital Equipment Corporation (DEC)'s PDP-10, later marketed as the DECsystem-10, is a mainframe computer family manufactured beginning in 1966 and discontinued in 1983. 1970s models and beyond were marketed under the DECsystem-10 name, especi ...
line of 36-bit computers in 1967. Before the widespread use of Unix, TOPS-10 was a particularly popular system in universities, and in the early
ARPANET The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switched network with distributed control and one of the first computer networks to implement the TCP/IP protocol suite. Both technologies became the tec ...
community. Bolt, Beranek, and Newman developed TENEX for a modified PDP-10 that supported
demand paging In computer operating systems, demand paging (as opposed to anticipatory paging) is a method of virtual memory management. In a system that uses demand paging, the operating system copies a disk page into physical memory only when an attempt is m ...
; this was another popular system in the research and ARPANET communities, and was later developed by DEC into
TOPS-20 The TOPS-20 operating system by Digital Equipment Corporation (DEC) is a proprietary OS used on some of DEC's 36-bit mainframe computers. The Hardware Reference Manual was described as for "DECsystem-10/DECSYSTEM-20 Processor" (meaning the DEC PDP ...
.
Scientific Data Systems Scientific Data Systems (SDS), was an American computer company founded in September 1961 by Max Palevsky, Arthur Rock and Robert Beck, veterans of Packard Bell Corporation and Bendix, along with eleven other computer scientists. SDS was the f ...
/Xerox Data Systems developed several operating systems for the Sigma series of computers, such as the Basic Control Monitor (BCM), Batch Processing Monitor (BPM), and Basic Time-Sharing Monitor (BTM). Later, BPM and BTM were succeeded by the Universal Time-Sharing System (UTS); it was designed to provide multi-programming services for online (interactive) user programs in addition to batch-mode production jobs, It was succeeded by the CP-V operating system, which combined UTS with the heavily batch-oriented Xerox Operating System.


Minicomputers

Digital Equipment Corporation created several operating systems for its 16-bit
PDP-11 The PDP–11 is a series of 16-bit minicomputers originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of a ...
machines, including the simple
RT-11 RT-11 (Real-time 11) is a discontinued small, low-end, single-user real-time operating system for the full line of Digital Equipment Corporation PDP-11 16-bit computers. RT-11 was first implemented in 1970. It was widely used for real-time compu ...
system, the time-sharing RSTS operating systems, and the
RSX-11 RSX-11 is a discontinued family of multi-user real-time operating systems for PDP-11 computers created by Digital Equipment Corporation. In widespread use through the late 1970s and early 1980s, RSX-11 was influential in the development of later ...
family of
real-time operating system A real-time operating system (RTOS) is an operating system (OS) for real-time computing applications that processes data and events that have critically defined time constraints. A RTOS is distinct from a time-sharing operating system, such as Unix ...
s, as well as the VMS system for the 32-bit VAX machines. Several competitors of Digital Equipment Corporation such as
Data General Data General Corporation was an early minicomputer firm formed in 1968. Three of the four founders were former employees of Digital Equipment Corporation (DEC). Their first product, 1969's Data General Nova, was a 16-bit minicomputer intended to ...
,
Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company. It was founded by Bill Hewlett and David Packard in 1939 in a one-car garage in Palo Alto, California ...
, and Computer Automation created their own operating systems. One such, "MAX III", was developed for Modular Computer Systems Modcomp II and Modcomp III computers. It was characterised by its target market being the industrial control market. The Fortran libraries included one that enabled access to measurement and control devices. IBM's key innovation in operating systems in this class (which they call "mid-range"), was their "CPF" for the
System/38 The System/38 is a discontinued minicomputer and midrange computer manufactured and sold by IBM. The system was announced in 1978. The System/38 has 48-bit computing, 48-bit addressing, which was unique for the time, and a novel database#Integrat ...
. This had capability-based addressing, used a machine interface architecture to isolate the application software and most of the operating system from hardware dependencies (including even such details as address size and register size) and included an integrated
RDBMS A relational database (RDB) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. A Relational Database Management System (RDBMS) is a type of database management system that stores data in a structured forma ...
. The succeeding OS/400 (now known as
IBM i IBM i (the ''i'' standing for ''integrated'') is an operating system developed by IBM for IBM Power Systems. It was originally released in 1988 as OS/400, as the sole operating system of the IBM AS/400 line of systems. It was renamed to i5/OS in 2 ...
) for the
IBM AS/400 The IBM AS/400 (Application System/400) is a family of midrange computers from IBM announced in June 1988 and released in August 1988. It was the successor to the System/36 and System/38 platforms, and ran the OS/400 operating system. Lower-cost b ...
and later
IBM Power Systems IBM Power Systems is a family of server computers from IBM that are based on its Power processors. It was created in 2008 as a merger of the System p and System i product lines. History IBM had two distinct POWER- and PowerPC-based hardwa ...
has no files, only objects of different types and these objects persist in very large, flat virtual memory, called a single-level store. The
Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
operating system was developed at AT&T Bell Laboratories in the late 1960s, originally for the
PDP-7 The PDP-7 is an 18-bit computing, 18-bit minicomputer produced by Digital Equipment Corporation as part of the Programmed Data Processor, PDP series. Introduced in 1964, shipped since 1965, it was the first to use their Flip-Chip module, Flip- ...
, and later for the PDP-11. Because it was essentially free in early editions, easily obtainable, and easily modified, it achieved wide acceptance. It also became a requirement within the Bell systems operating companies. Since it was written in the
C language C (''pronounced'' '' – like the letter c'') is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities o ...
, when that language was ported to a new machine architecture, Unix was also able to be ported. This portability permitted it to become the choice for a second generation of minicomputers and the first generation of
workstation A workstation is a special computer designed for technical or computational science, scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating syste ...
s, and its use became widespread. Unix exemplified the idea of an operating system that was conceptually the same across various hardware platforms. Because of its utility, it inspired many and later became one of the roots of the
free software Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...
movement and
open-source software Open-source software (OSS) is Software, computer software that is released under a Open-source license, license in which the copyright holder grants users the rights to use, study, change, and Software distribution, distribute the software an ...
. Numerous operating systems were based upon it including
Minix MINIX is a Unix-like operating system based on a microkernel Software architecture, architecture, first released in 1987 and written by American-Dutch computer scientist Andrew S. Tanenbaum. It was designed as a clone of the Unix operating syste ...
, GNU/Linux, and the
Berkeley Software Distribution The Berkeley Software Distribution (BSD), also known as Berkeley Unix or BSD Unix, is a discontinued Unix operating system developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, beginn ...
. Apple's
macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...
is also based on Unix via
NeXTSTEP NeXTSTEP is a discontinued object-oriented, multitasking operating system based on the Mach kernel and the UNIX-derived BSD. It was developed by NeXT, founded by Steve Jobs, in the late 1980s and early 1990s and was initially used for its ...
and
FreeBSD FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable ...
. The
Pick operating system The Pick Operating System, also known as the Pick System or simply Pick, is a demand-paged, multi-user, virtual memory, time-sharing computer operating system based around a MultiValue database. Pick is used primarily for business data processin ...
was another operating system available on a wide variety of hardware brands. Commercially released in 1973 its core was a
BASIC Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * Basic (film), ''Basic'' (film), a 2003 film ...
-like language called Data/BASIC and a SQL-style database manipulation language called ENGLISH. Licensed to a large variety of manufacturers and vendors, by the early 1980s observers saw the Pick operating system as a strong competitor to Unix.


Microcomputers

Beginning in the mid-1970s, a new class of small computers came onto the marketplace. Featuring 8-bit processors, typically the
MOS Technology 6502 The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit computing, 8-bit microprocessor that was desi ...
,
Intel 8080 The Intel 8080 is Intel's second 8-bit computing, 8-bit microprocessor. Introduced in April 1974, the 8080 was an enhanced successor to the earlier Intel 8008 microprocessor, although without binary compatibility.'' Electronic News'' was a week ...
,
Motorola 6800 The 6800 ("''sixty-eight hundred''") is an 8-bit microprocessor designed and first manufactured by Motorola in 1974. The MC6800 microprocessor was part of the M6800 Microcomputer System (later dubbed ''68xx'') that also included serial and parall ...
or the
Zilog Z80 The Zilog Z80 is an 8-bit computing, 8-bit microprocessor designed by Zilog that played an important role in the evolution of early personal computing. Launched in 1976, it was designed to be Backward compatibility, software-compatible with the ...
, along with rudimentary input and output interfaces and as much
RAM Ram, ram, or RAM most commonly refers to: * A male sheep * Random-access memory, computer memory * Ram Trucks, US, since 2009 ** List of vehicles named Dodge Ram, trucks and vans ** Ram Pickup, produced by Ram Trucks Ram, ram, or RAM may also ref ...
as practical, these systems started out as kit-based hobbyist computers but soon evolved into an essential business tool.


Home computers

While many eight-bit
home computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a s ...
s of the 1980s, such as the
BBC Micro The BBC Microcomputer System, or BBC Micro, is a family of microcomputers developed and manufactured by Acorn Computers in the early 1980s as part of the BBC's Computer Literacy Project. Launched in December 1981, it was showcased across severa ...
,
Commodore 64 The Commodore 64, also known as the C64, is an 8-bit computing, 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in ...
,
Apple II Apple II ("apple Roman numerals, two", stylized as Apple ][) is a series of microcomputers manufactured by Apple Computer, Inc. from 1977 to 1993. The Apple II (original), original Apple II model, which gave the series its name, was designed ...
, Atari 8-bit computers, Amstrad CPC, ZX Spectrum series and others could load a third-party disk-loading operating system, such as
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, Dig ...
or GEOS (8-bit operating system), GEOS, they were generally used without one. Their built-in operating systems were designed in an era when floppy disk drives were very expensive and not expected to be used by most users, so the standard storage device on most was a
tape drive A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic-tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability. ...
using standard compact cassettes. Most, if not all, of these computers shipped with a built-in
BASIC Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * Basic (film), ''Basic'' (film), a 2003 film ...
interpreter on ROM, which also served as a crude
command-line interface A command-line interface (CLI) is a means of interacting with software via command (computing), commands each formatted as a line of text. Command-line interfaces emerged in the mid-1960s, on computer terminals, as an interactive and more user ...
, allowing the user to load a separate
disk operating system A disk operating system (DOS) is a computer operating system that requires a disk or other direct-access storage device as secondary storage. A DOS provides a file system and a means for loading and running computer program, programs stored on th ...
to perform file management commands and load and save to disk. The most popular home computer, the Commodore 64, was a notable exception, as its DOS was on ROM in the disk drive hardware, and the drive was addressed identically to printers, modems, and other external devices. Furthermore, those systems shipped with minimal amounts of
computer memory Computer memory stores information, such as data and programs, for immediate use in the computer. The term ''memory'' is often synonymous with the terms ''RAM,'' ''main memory,'' or ''primary storage.'' Archaic synonyms for main memory include ...
—4-8
kilobyte The kilobyte is a multiple of the unit byte for Computer data storage, digital information. The International System of Units (SI) defines the prefix ''kilo-, kilo'' as a multiplication factor of 1000 (103); therefore, one kilobyte is 1000&nbs ...
s was standard on early home computers—as well as 8-bit processors without specialized support circuitry like an MMU or even a dedicated
real-time clock A real-time clock (RTC) is an electronic device (most often in the form of an integrated circuit) that measures the passage of time. Although the term often refers to the devices in personal computers, server (computing), servers and embedded ...
. On this hardware, a complex operating system's overhead supporting multiple tasks and users would likely compromise the performance of the machine without really being needed. As those systems were largely sold complete, with a fixed hardware configuration, there was also no need for an operating system to provide drivers for a wide range of hardware to abstract away differences.
Video game A video game or computer game is an electronic game that involves interaction with a user interface or input device (such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device) to generate visual fe ...
s and even the available
spreadsheet A spreadsheet is a computer application for computation, organization, analysis and storage of data in tabular form. Spreadsheets were developed as computerized analogs of paper accounting worksheets. The program operates on data entered in c ...
,
database In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and a ...
and
word processor A word processor (WP) is a device or computer program that provides for input, editing, formatting, and output of text, often with some additional features. Early word processors were stand-alone devices dedicated to the function, but current word ...
s for home computers were mostly self-contained programs that took over the machine completely. Although
integrated software Integrated software is a software for personal computers that combines the most commonly used functions of many productivity software programs into one application. The integrated software genre has been largely overshadowed by fully functional o ...
existed for these computers, they usually lacked features compared to their standalone equivalents, largely due to memory limitations. Data exchange was mostly performed through standard formats like
ASCII ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...
text or CSV, or through specialized file conversion programs.


Operating systems in video games and consoles

Since virtually all video game consoles and arcade cabinets designed and built after 1980 were true digital machines based on
microprocessor A microprocessor is a computer processor (computing), processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, a ...
s (unlike the earlier ''
Pong ''Pong'' is a 1972 sports video game developed and published by Atari for arcades. It is one of the earliest arcade video games; it was created by Allan Alcorn as a training exercise assigned to him by Atari co-founder Nolan Bushnell, but B ...
'' clones and derivatives), some of them carried a minimal form of
BIOS In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is a type of firmware used to provide runtime services for operating systems and programs and to perform hardware initialization d ...
or built-in game, such as the
ColecoVision ColecoVision is a second-generation home video-game console developed by Coleco and launched in North America in August 1982. It was released a year later in Europe by CBS Electronics as the CBS ColecoVision. The console offered a closer expe ...
, the Sega Master System and the SNK
Neo Geo The , stylized as NEO•GEO, is a video game platform released in 1990 by Japanese game company SNK Corporation. It was initially released in two ROM cartridge-based formats: an arcade system board (Multi Video System; MVS) and a home video gam ...
. Modern-day game consoles and videogames, starting with the
PC-Engine The TurboGrafx-16, known in Japan as the , is a home video game console developed by Hudson Soft and manufactured by NEC. It was released in Japan in 1987 and in North America in 1989. The first console of the fourth generation, it launched in ...
, all have a minimal BIOS that also provides some interactive utilities such as
memory card A memory card is an electronic data storage device used for storing digital information, typically using flash memory. These are commonly used in digital portable electronic devices, such as digital cameras as well as in many early games conso ...
management,
audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum *Digital audio, representation of sound ...
or
video CD Video CD (abbreviated as VCD, and also known as Compact Disc Digital Video), (not to be confused with CD Video which is a type of Laserdisc) is a home video format and the first format for distributing films on standard optical discs. The f ...
playback,
copy protection Copy protection, also known as content protection, copy prevention and copy restriction, is any measure to enforce copyright by preventing the reproduction of software, films, music, and other media. Copy protection is most commonly found on vid ...
and sometimes carry
libraries A library is a collection of Book, books, and possibly other Document, materials and Media (communication), media, that is accessible for use by its members and members of allied institutions. Libraries provide physical (hard copies) or electron ...
for developers to use etc. Few of these cases, however, would qualify as a true operating system. The most notable exceptions are probably the
Dreamcast The is the final home video game console manufactured by Sega. It was released in Japan on November 27, 1998, in North America on September 9, 1999 and in Europe on October 14, 1999. It was the first sixth-generation video game console, prec ...
game console which includes a minimal BIOS, like the
PlayStation is a video gaming brand owned and produced by Sony Interactive Entertainment (SIE), a division of Japanese conglomerate Sony. Its flagship products consists of a series of home video game consoles produced under the brand; it also consists ...
, but can load the
Windows CE Windows CE, later known as Windows Embedded CE and Windows Embedded Compact, is a discontinued operating system developed by Microsoft for mobile and embedded devices. It was part of the Windows Embedded family and served as the software foun ...
operating system from the game disk allowing easily porting of games from the PC world, and the
Xbox Xbox is a video gaming brand that consists of four main home video game console lines, as well as application software, applications (games), the streaming media, streaming service Xbox Cloud Gaming, and online services such as the Xbox networ ...
game console, which is little more than a disguised Intel-based PC running a secret, modified version of
Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
in the background. Furthermore, there are
Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...
versions that will run on a
Dreamcast The is the final home video game console manufactured by Sega. It was released in Japan on November 27, 1998, in North America on September 9, 1999 and in Europe on October 14, 1999. It was the first sixth-generation video game console, prec ...
and later game consoles as well. Long before that,
Sony is a Japanese multinational conglomerate (company), conglomerate headquartered at Sony City in Minato, Tokyo, Japan. The Sony Group encompasses various businesses, including Sony Corporation (electronics), Sony Semiconductor Solutions (i ...
had released a kind of development kit called the
Net Yaroze The is a Game development kit, development kit for the PlayStation (console), PlayStation video game console. It was a promotion by Sony Computer Entertainment to computer programming hobbyists which launched in June 1996 in Japan and in 1997 in ...
for its first PlayStation platform, which provided a series of programming and developing tools to be used with a normal PC and a specially modified "Black PlayStation" that could be interfaced with a PC and download programs from it. These operations require in general a functional OS on both platforms involved. In general, it can be said that videogame consoles and arcade coin-operated machines used at most a built-in
BIOS In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is a type of firmware used to provide runtime services for operating systems and programs and to perform hardware initialization d ...
during the 1970s, 1980s and most of the 1990s, while from the PlayStation era and beyond they started getting more and more sophisticated, to the point of requiring a generic or custom-built OS for aiding in development and expandability.


Personal computer era

The development of microprocessors made inexpensive computing available for the
small business Small businesses are types of corporations, partnerships, or sole proprietorships which have a small number of employees and/or less annual revenue than a regular-sized business or corporation. Businesses are defined as "small" in terms of being ...
and hobbyist, which in turn led to the widespread use of interchangeable hardware components using a common interconnection (such as the S-100, SS-50,
Apple II Apple II ("apple Roman numerals, two", stylized as Apple ][) is a series of microcomputers manufactured by Apple Computer, Inc. from 1977 to 1993. The Apple II (original), original Apple II model, which gave the series its name, was designed ...
, ISA, and PCI
bus A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a motor vehicle that carries significantly more passengers than an average car or van, but fewer than the average rail transport. It is most commonly used ...
es), and an increasing need for "standard" operating systems to control them. The most important of the early OSes on these machines was
Digital Research Digital Research, Inc. (DR or DRI) was a privately held American software company created by Gary Kildall to market and develop his CP/M operating system and related 8-bit, 16-bit and 32-bit systems like MP/M, Concurrent DOS, FlexOS, Multiuser ...
's
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, Dig ...
-80 for the 8080 / 8085 / Z-80 CPUs. It was based on several Digital Equipment Corporation operating systems, mostly for the PDP-11 architecture. Microsoft's first operating system, MDOS/MIDAS, was designed along many of the PDP-11 features, but for microprocessor based systems.
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 op ...
, or
PC DOS PC or pc may refer to: Arts and entertainment * Player character or playable character, a fictional character controlled by a human player, usually in role-playing games or computer games * '' Port Charles'', an American daytime TV soap opera * ...
when supplied by IBM, was designed to be similar to CP/M-80. Each of these machines had a small boot program in ROM which loaded the OS itself from disk. The BIOS on the IBM-PC class machines was an extension of this idea and has accreted more features and functions in the 20 years since the first IBM-PC was introduced in 1981. The decreasing cost of display equipment and processors made it practical to provide graphical user interfaces for many operating systems, such as the generic
X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X originated as part of Project Athena at Massachusetts Institute of Technology (MIT) in 1984. The X protocol has been at ...
that is provided with many Unix systems, or other graphical systems such as
Apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...
's
classic Mac OS Mac OS (originally System Software; retronym: Classic Mac OS) is the series of operating systems developed for the Mac (computer), Macintosh family of personal computers by Apple Computer, Inc. from 1984 to 2001, starting with System 1 and end ...
and
macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...
, the
Radio Shack RadioShack (formerly written as Radio Shack) is an American electronics retailer that was established in 1921 as an amateur radio mail-order business. Its parent company was purchased by Tandy Corporation in 1962, which shifted its focus from ma ...
Color Computer's OS-9 Level II/Multi-Vue, Commodore's
AmigaOS AmigaOS is a family of proprietary native operating systems of the Amiga and AmigaOne personal computers. It was developed first by Commodore International and introduced with the launch of the first Amiga, the Amiga 1000, in 1985. Early versions ...
,
Atari TOS TOS (The Operating System) is the operating system of the Atari ST range of computers. This range includes the 520ST and 1040ST, their STF/M/FM and STE variants and the Mega ST/STE. Later, 32-bit machines ( TT, Falcon030) were developed using a ...
,
IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
's
OS/2 OS/2 is a Proprietary software, proprietary computer operating system for x86 and PowerPC based personal computers. It was created and initially developed jointly by IBM and Microsoft, under the leadership of IBM software designer Ed Iacobucci, ...
, and
Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
. The original GUI was developed on the
Xerox Alto The Xerox Alto is a computer system developed at Xerox PARC (Palo Alto Research Center) in the 1970s. It is considered one of the first workstations or personal computers, and its development pioneered many aspects of modern computing. It featu ...
computer system at Xerox Palo Alto Research Center in the early 1970s and commercialized by many vendors throughout the 1980s and 1990s. Since the late 1990s, there have been three operating systems in widespread use on personal computers:
Apple Inc. Apple Inc. is an American multinational corporation and technology company headquartered in Cupertino, California, in Silicon Valley. It is best known for its consumer electronics, software, and services. Founded in 1976 as Apple Comput ...
's
macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...
, the
open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...
Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...
, and
Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
. Since 2005 and the Mac transition to Intel processors, all have been developed mainly on the
x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel, based on the 8086 microprocessor and its 8-bit-external-bus variant, the 8088. Th ...
platform, although macOS retained
PowerPC PowerPC (with the backronym Performance Optimization With Enhanced RISC – Performance Computing, sometimes abbreviated as PPC) is a reduced instruction set computer (RISC) instruction set architecture (ISA) created by the 1991 Apple Inc., App ...
support until 2009 and Linux remains ported to a multitude of architectures including ones such as 68k,
PA-RISC Precision Architecture reduced instruction set computer, RISC (PA-RISC) or Hewlett Packard Precision Architecture (HP/PA or simply HPPA), is a computer, general purpose computer instruction set architecture (ISA) developed by Hewlett-Packard f ...
, and
DEC Alpha Alpha (original name Alpha AXP) is a 64-bit reduced instruction set computer (RISC) instruction set architecture (ISA) developed by Digital Equipment Corporation (DEC). Alpha was designed to replace 32-bit VAX complex instruction set computers ( ...
, which have been long superseded and out of production, and SPARC and MIPS, which are used in servers or embedded systems but no longer for desktop computers. Other operating systems such as AmigaOS and OS/2 remain in use, if at all, mainly by
retrocomputing Retrocomputing is the current use of Vintage computer, older computer hardware and software. Retrocomputing is usually classed as a hobby and recreation rather than a practical application of technology; enthusiasts often collect rare and valuabl ...
enthusiasts or for specialized embedded applications.


Mobile operating systems

In the early 1990s, Psion released the Psion Series 3 PDA, a small mobile computing device. It supported user-written applications running on an operating system called EPOC. Later versions of EPOC became
Symbian Symbian is a discontinued mobile operating system (OS) and computing platform designed for smartphones. It was originally developed as a proprietary software OS for personal digital assistants in 1998 by the Symbian Ltd. consortium. Symbian OS ...
, an operating system used for mobile phones from
Nokia Nokia Corporation is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporation, originally established as a pulp mill in 1 ...
,
Ericsson (), commonly known as Ericsson (), is a Swedish multinational networking and telecommunications company headquartered in Stockholm, Sweden. Ericsson has been a major contributor to the development of the telecommunications industry and is one ...
,
Sony Ericsson Sony Mobile Communications Inc., originally Sony Ericsson Mobile Communications AB, was a Multinational corporation, multinational consumer electronics and telecommunications company, best known for its Mobile phones, mobile phone products. The ...
,
Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois. It was founded by brothers Paul and Joseph Galvin in 1928 and had been named Motorola since 1947. Many of Motorola's products had been ...
,
Samsung Samsung Group (; stylised as SΛMSUNG) is a South Korean Multinational corporation, multinational manufacturing Conglomerate (company), conglomerate headquartered in the Samsung Town office complex in Seoul. The group consists of numerous a ...
and phones developed for NTT Docomo by Sharp, Fujitsu &
Mitsubishi The is a group of autonomous Japanese multinational companies in a variety of industries. Founded by Yatarō Iwasaki in 1870, the Mitsubishi Group traces its origins to the Mitsubishi zaibatsu, a unified company that existed from 1870 to 194 ...
.
Symbian Symbian is a discontinued mobile operating system (OS) and computing platform designed for smartphones. It was originally developed as a proprietary software OS for personal digital assistants in 1998 by the Symbian Ltd. consortium. Symbian OS ...
was the world's most widely used smartphone operating system until 2010 with a peak market share of 74% in 2006. In 1996, Palm Computing released the
Pilot 1000 The Pilot 1000 and Pilot 5000 are the first generations of PDAs produced by Palm Computing (then a subsidiary of U.S. Robotics). It was introduced in March 1996. The Pilot uses a Motorola 68328 processor at 16 MHz, and had 128 kB (Pilo ...
and Pilot 5000, running
Palm OS Palm OS (also known as Garnet OS) is a discontinued mobile operating system initially developed by Palm, Inc., for personal digital assistants (PDAs) in 1996. Palm OS was designed for ease of use with a touchscreen-based graphical user interface. ...
. Microsoft
Windows CE Windows CE, later known as Windows Embedded CE and Windows Embedded Compact, is a discontinued operating system developed by Microsoft for mobile and embedded devices. It was part of the Windows Embedded family and served as the software foun ...
was the base for Pocket PC 2000, renamed
Windows Mobile Windows Mobile is a discontinued mobile operating system developed by Microsoft for smartphones and personal digital assistants (PDA). Designed to be the portable equivalent of the Windows desktop OS in the emerging Mobile device, mobile/port ...
in 2003, which at its peak in 2007 was the most common operating system for smartphones in the U.S. In 2007, Apple introduced the
iPhone The iPhone is a line of smartphones developed and marketed by Apple that run iOS, the company's own mobile operating system. The first-generation iPhone was announced by then–Apple CEO and co-founder Steve Jobs on January 9, 2007, at ...
and its operating system, known as simply iPhone OS (until the release of
iOS 4 iOS 4 is the fourth major release of the iOS mobile operating system developed by Apple Inc., being the successor to iPhone OS 3. It was announced at the Apple Special Event on April 8, 2010, and released on June 21, 2010. iOS 4 was the first ...
), which, like
Mac OS X macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...
, is based on the
Unix-like A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...
Darwin. In addition to these underpinnings, it also introduced a powerful and innovative graphic user interface that was later also used on the
tablet computer A tablet computer, commonly shortened to tablet, is a mobile device, typically with a mobile operating system and touchscreen display processing circuitry, and a rechargeable battery in a single, thin and flat package. Tablets, being computers ...
iPad The iPad is a brand of tablet computers developed and marketed by Apple Inc., Apple that run the company's mobile operating systems iOS and later iPadOS. The IPad (1st generation), first-generation iPad was introduced on January 27, 2010. ...
. A year later, Android, with its own graphical user interface, was introduced, based on a modified
Linux kernel The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the k ...
, and
Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...
re-entered the mobile operating system market with
Windows Phone Windows Phone (WP) is a discontinued mobile operating system developed by Microsoft Mobile for smartphones as the replacement successor to Windows Mobile and Zune. Windows Phone featured a new user interface derived from the Metro design languag ...
in 2010, which was replaced by
Windows 10 Mobile Windows 10 Mobile is the fourth and final generation of Microsoft's Windows Phone mobile operating system, succeeding Windows Phone 8.1. First released in 2015, it was marketed by Microsoft as being an Windows 10 editions, edition of its Per ...
in 2015. In addition to these, a wide range of other
mobile operating system A mobile operating system is an operating system used for smartphones, tablets, smartwatches, smartglasses, or other non-laptop personal mobile computing devices. While computers such as laptops are "mobile", the operating systems used on the ...
s are contending in this area.


Rise of virtualization

Operating systems originally ran directly on the hardware itself and provided services to applications, but with virtualization, the operating system itself runs under the control of a
hypervisor A hypervisor, also known as a virtual machine monitor (VMM) or virtualizer, is a type of computer software, firmware or hardware that creates and runs virtual machines. A computer on which a hypervisor runs one or more virtual machines is called ...
, instead of being in direct control of the hardware. On mainframes IBM introduced the notion of a
virtual machine In computing, a virtual machine (VM) is the virtualization or emulator, emulation of a computer system. Virtual machines are based on computer architectures and provide the functionality of a physical computer. Their implementations may involve ...
in 1968 with CP/CMS on the
IBM System/360 Model 67 IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the computer market with the 7000 series and the later System/360, followed by the System/370. Current mainframe computers in IBM' ...
, and extended this later in 1972 with Virtual Machine Facility/370 (VM/370) on
System/370 The IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the IBM System/360, System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migrati ...
. On
x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel, based on the 8086 microprocessor and its 8-bit-external-bus variant, the 8088. Th ...
-based
personal computer A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as Word processor, word processing, web browser, internet browsing, email, multimedia playback, and PC ...
s, VMware popularized this technology with their 1999 product,
VMware Workstation VMware Workstation Pro (known as VMware Workstation until release of VMware Workstation 12 in 2015) is a hosted (Type 2) hypervisor that runs on x64 versions of Windows and Linux operating systems. It enables users to set up virtual machines (VM ...
, and their 2001 VMware GSX Server and VMware ESX Server products. Later, a wide range of products from others, including Xen, KVM and
Hyper-V Hyper-V is a native hypervisor developed by Microsoft; it can create virtual machines on x86-64 systems running Windows. It is included in Pro and Enterprise editions of Windows (since Windows 8) as an optional feature to be manually enabled. A ...
meant that by 2010 it was reported that more than 80 percent of enterprises had a virtualization program or project in place, and that 25 percent of all server workloads would be in a virtual machine. Over time, the line between virtual machines, monitors, and operating systems was blurred: * Hypervisors grew more complex, gaining their own application programming interface, memory management or file system. * Virtualization becomes a key feature of operating systems, as exemplified by KVM and
LXC Linux Containers (LXC) is an operating system-level virtualization method for running multiple isolated Linux systems (containers) on a control host using a single Linux kernel. The Linux kernel provides the cgroups functionality that allows l ...
in Linux,
Hyper-V Hyper-V is a native hypervisor developed by Microsoft; it can create virtual machines on x86-64 systems running Windows. It is included in Pro and Enterprise editions of Windows (since Windows 8) as an optional feature to be manually enabled. A ...
in
Windows Server 2008 Windows Server 2008, codenamed "Longhorn Server" (alternatives: "Windows Vista Server" or "Windows Server Vista"), is the seventh major version of the Windows NT operating system produced by Microsoft to be released under the Windows Server b ...
or HP Integrity Virtual Machines in
HP-UX HP-UX (from "Hewlett Packard Unix") is a proprietary software, proprietary implementation of the Unix operating system developed by Hewlett Packard Enterprise; current versions support HPE Integrity Servers, based on Intel's Itanium architect ...
. * In some systems, such as
POWER5 The POWER5 is a microprocessor developed and fabricated by IBM. It is an improved version of the POWER4. The principal improvements are support for simultaneous multithreading (SMT) and an on-die memory controller. The POWER5 is a dual-core ...
and later POWER servers from IBM, the hypervisor is no longer optional. * Radically simplified operating systems, such as CoreOS have been designed to run only on virtual systems. * Applications have been re-designed to run directly on a virtual machine monitor. In many ways, virtual machine software today plays the role formerly held by the operating system, including managing the hardware resources (processor, memory, I/O devices), applying scheduling policies, or allowing system administrators to manage the system.


See also

*
Charles Babbage Institute The IT History Society (ITHS) is an organization that supports the history and scholarship of information technology by encouraging, fostering, and facilitating archival and historical research. Formerly known as the Charles Babbage Foundation, ...
*
IT History Society The IT History Society (ITHS) is an organization that supports the history and scholarship of information technology by encouraging, fostering, and facilitating archival and historical research. Formerly known as the Charles Babbage Foundation, ...
* List of operating systems * Timeline of operating systems * History of computer icons


Notes


References


Further reading

* {{Operating system
Operating systems An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...
*History History of computing Software topical history overviews