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Time-sharing

In computing, time-sharing is the concurrent sharing of a computing resource among many tasks or users by giving each task or user a small slice of processing time. This quick switch between tasks or users gives the illusion of simultaneous execution.[1][2] It enables multi-tasking by a single user or enables multiple-user sessions.

This article is about the computing term. For the type of property ownership, see Timeshare. For time sharing of communications media, see Time-division multiple access.

Developed during the 1960s, its emergence as the prominent model of computing in the 1970s represented a major technological shift in the history of computing. By allowing many users to interact concurrently with a single computer, time-sharing dramatically lowered the cost of providing computing capability, made it possible for individuals and organizations to use a computer without owning one,[3] and promoted the interactive use of computers and the development of new interactive applications.

(TSL, 1969–1974) - launched using DEC systems. PERT was one of its popular offerings. TSL was acquired by ADP in 1974.

Time Sharing Limited

OLS Computer Services (UK) Limited (1975–1980) - using HP & DEC systems.

RUSH (Remote Users of Shared Hardware) Time-sharing System on IBM S/360 hardware (1966)[46]Tymshare

Allen-Babcock

Bell Labs Unix (1971) → UC Berkeley BSD Unix (1977)

AT&T

PDP-1 Time-sharing System → Massachusetts General Hospital PDP-1D → MUMPS

BBN

TENEXDEC TOPS-20, Foonly FOONEX, MAXC OS at PARC, Stanford Low Overhead TimeSharing (LOTS), which ran TOPS-20

BBN

at UC Berkeley Project GenieScientific Data Systems SDS 940 (Tymshare, BBN, SRI, Community Memory) → BCC 500 → MAXC at PARC

Berkeley Timesharing System

Time-sharing MCPHP 3000 MPE

Burroughs

Cambridge Multiple Access System was developed for the , the prototype Atlas 2 computer built by Ferranti for the University of Cambridge.[47] This was the first time-sharing system developed outside the United States, and which influenced the later development of UNIX.

Titan

Compower Ltd., a wholly owned subsidiary of the National Coal Board (later British Coal Corporation) in the UK. Originally National Coal Board (NCB) Computer Services, it became Compower in 1973 providing computing and time-share services to internal NCB users and as a commercial service to external users. Sold to Philips C&P (Communications and Processing) in August 1994.

also branded as Compu-Serv, CIS.

CompuServe

Compu-Time, Inc., on Honeywell 400/4000, started in 1968 in Ft Lauderdale, Florida, moved to Daytona Beach in 1970.

[29]

MACE, APEX → KronosNOSNOS/VE

CDC

(DTSS) → GE Time-sharing → GEnie

Dartmouth Time Sharing System

PDP-6 Time-sharing Monitor → TOPS-10BBN TENEX → DEC TOPS-20

DEC

TSS/8RSTS-11, RSX-11OpenVMS

DEC

COTAN (Culham Online Task Activation Network)

English Electric KDF9

CALL/360, CALL/OS - using IBM System/360 Model 50

IBM

CP-67CP-370CP/CMSVM/CMS

IBM CP-40

TSO for OS/MVT → for OS/VS2 → for MVS → for z/OS

IBM

TSS/360 → TSS/370

IBM

GEORGE 3 MOP (Multiple Online Programming)

ICT 1900 series

International Timesharing Corporation on dual systems.[29]

CDC 3300

Linux: see how it evolved from MIT CTSS

CTSSMULTICS (MIT / GE / Bell Labs) → UnixLinux

MIT

Time-sharing System for the DEC PDP-1ITS

MIT

MUSIC → IBM MUSIC/SP

McGill University

on the IBM S/360-67, S/370, and successors.

Michigan Terminal System

CDC SCOPE/HUSTLER System

Michigan State University

VP/CSS, on IBM 360 series; originally based on IBM's CP/CMS.

National CSS

OS-3, on CDC 3000 series.

Oregon State University

PRIMOS

Prime Computer

JOSS → JOSS-2 → JOSS-3

RAND

TSOSUnivac / Unisys VMOS → VS/9

RCA

on CDC 6600 Kronos.

Service in Informatics and Analysis (SIA)

Time-sharing System, on the AN/FSQ-32.

System Development Corporation

PDP-1 Time-sharing System → SAILWAITS

Stanford

(TSL)[48] on DEC PDP-10 systems → Automatic Data Processing (ADP), first commercial time-sharing system in Europe and first dual (fault tolerant) time-sharing system.

Time Sharing Ltd.

(TSO-like, for VS1), a non-IBM Time-sharing product, marketed by Tone Software Co; TSO required VS2.

Tone

SDS-940 → Tymcom X → Tymcom XX

Tymshare

/UNIVAC 1108 EXEC 8 → OS 1100 → OS 2200

Unisys

CAL-TSS, on CDC 6400.

UC Berkeley

UTSCP-VHoneywell CP-6

XDS

Significant early timesharing systems:[29]

Cloud computing

, a 1972 film.

The Heralds of Resource Sharing

IBM's virtual machine operating system (CP) that supported time-sharing (CMS).

History of CP/CMS

an experimental computer system based on an IBM 7044 used to simulate multiple virtual machines.

IBM M44/44X

the only IBM S/360 series mainframe to support virtual memory.

IBM System/360 Model 67

multiple users on a single personal computer.

Multiseat configuration

a DARPA funded project at MIT famous for groundbreaking research in operating systems, artificial intelligence, and the theory of computation.

Project MAC

an interactive, conversational programming language based on JOSS, developed by BBN in 1964.

TELCOMP

Timeline of operating systems

(Virtual Address eXtension), a computer architecture and family of computers developed by DEC.

VAX

Utility computing

Virtual memory

Time-sharing system evolution

(1974). Computer Lib: You Can and Must Understand Computers Now; Dream Machines: "New Freedoms Through Computer Screens— A Minority Report". Self-published. ISBN 0-89347-002-3. pp. 56–57.

Nelson, Theodor

Fredkin, Edward (Nov 1963). (PDF). Computers and Automation. XII (11): 12–13, 16–20.: "The author relates a short history of time-sharing, the initial time-sharing experiments, the modifications of existing computers and those designed specifically for time-sharing, project MAC, significant features of the system, services, languages, programs, scope displays and light pens, and intercommunication.[1]

"The Time Sharing of Computers"

Alexander, Michael T. (May 1971). Time Sharing Supervisor Programs (Thesis). :2027.42/79614.

hdl

Robert Frankston's MIT Master's Thesis, 1973.

"The Computer Utility As A Marketplace For Computer Services"

an interview with Professor Fernando J. Corbató on the history of Multics and origins of time-sharing, 2009.

"40 years of Multics, 1969-2009"

Revolution: The First 2000 Years of Computing, Computer History Museum Exhibition, January 2011.

"Mainframe Computers: The Virtues of Sharing"

Revolution: The First 2000 Years of Computing, Computer History Museum Exhibition, January 2011.

"Mainframe Computers: Timesharing as a Business"