Time-sharing
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In computing, time-sharing is the sharing of a computing resource among many tasks or users. It enables multi-tasking by a single user or enables multiple-user sessions.
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,[1] and promoted the interactive use of computers and the development of new interactive applications.
History
Batch processing
The earliest computers were extremely expensive devices, and very slow in comparison to later models. Machines were typically dedicated to a particular set of tasks and operated by control panels, the operator manually entering small programs via switches in order to load and run a series of programs. These programs might take hours to run. As computers grew in speed,
Comparatively inexpensive
The alternative of allowing the user to operate the computer directly was generally far too expensive to consider. This was because users might have long periods of entering code while the computer remained idle. This situation limited interactive development to those organizations that could afford to waste computing cycles: large universities for the most part.
Time-sharing
The concept is claimed to have been first described by Robert Dodds in a letter he wrote in 1949 although he did not use the term time-sharing.[4] Later John Backus also described the concept, but did not use the term, in the 1954 summer session at MIT.[5] Bob Bemer used the term time-sharing in his 1957 article "How to consider a computer" in Automatic Control Magazine and it was reported the same year he used the term time-sharing in a presentation.[4][6][7] In a paper published in December 1958, W. F. Bauer wrote that "The computers would handle a number of problems concurrently. Organizations would have input-output equipment installed on their own premises and would buy time on the computer much the same way that the average household buys power and water from utility companies."[8]
Christopher Strachey, who became Oxford University's first professor of computation, filed a patent application for "time-sharing" in February 1959.[9][10] He gave a paper "Time Sharing in Large Fast Computers"[11] at the first UNESCO Information Processing Conference in Paris in June that year, where he passed the concept on to J. C. R. Licklider.[12] This paper was credited by the MIT Computation Center in 1963 as "the first paper on time-shared computers".[13]
The meaning of the term time-sharing has shifted from its original usage. From 1949 to 1960, time-sharing was used to refer to
There are also examples of systems which provide multiple user consoles but only for specific applications, they are not general-purpose systems. These include SAGE (1958), SABRE (1960)[4] and PLATO II (1961), created by Donald Bitzer at a public demonstration at Robert Allerton Park near the University of Illinois in early 1961. Bitzer has long said that the PLATO project would have gotten the patent on time-sharing if only the University of Illinois had not lost the patent for two years.[14]
The first
JOSS began time-sharing service in January 1964.[19] Dartmouth Time Sharing System (DTSS) began service in March 1964.[20]
Development
Throughout the late 1960s and the 1970s,
DTSS's creators wrote in 1968 that "any response time which averages more than 10 seconds destroys the illusion of having one's own computer".[21] Conversely, timesharing users thought that their terminal was the computer.[22] It was an efficient way to share a large computer. As of 1972[update] DTSS supported more than 100 simultaneous users. Although more than 1,000 of the 19,503 jobs the system completed on "a particularly busy day" required ten seconds or more of computer time, DTSS was able to handle the jobs because 78% of jobs needed one second or less of computer time. About 75% of 3,197 users used their terminal for 30 minutes or less, during which they used less than four seconds of computer time. A football simulation, among early mainframe games written for DTSS, used less than two seconds of computer time during the 15 minutes of real time for playing the game.[23] With the rise of microcomputing in the early 1980s, time-sharing became less significant, because individual microprocessors were sufficiently inexpensive that a single person could have all the CPU time dedicated solely to their needs, even when idle.
However, the Internet brought the general concept of time-sharing back into popularity. Expensive corporate server farms costing millions can host thousands of customers all sharing the same common resources. As with the early serial terminals, web sites operate primarily in bursts of activity followed by periods of idle time. This bursting nature permits the service to be used by many customers at once, usually with no perceptible communication delays, unless the servers start to get very busy.
Time-sharing business
Genesis
In the 1960s, several companies started providing time-sharing services as
Common systems used for time-sharing included the
Rise and fall
In 1975, acting president of Prime Computer Ben F. Robelen told stockholders that "The biggest end-user market currently is time-sharing."[29] For DEC, for a while the second largest computer company (after IBM), this was also true: Their PDP-10 and IBM's 360/67[30] were widely used[31] by commercial timesharing services such as CompuServe, On-Line Systems, Inc. (OLS), Rapidata and Time Sharing Ltd.
The advent of the personal computer marked the beginning of the decline of time-sharing.[citation needed] The economics were such that computer time went from being an expensive resource that had to be shared to being so cheap that computers could be left to sit idle for long periods in order to be available as needed.[citation needed]
Rapidata as an example
Although many time-sharing services simply closed, Rapidata
UK
- ADPin 1974.
- OLS Computer Services (UK) Limited (1975–1980) - using HP & DEC systems.
The computer utility
Beginning in 1964, the
Security
Time-sharing was the first time that multiple processes, owned by different users, were running on a single machine, and these processes could interfere with one another.[41] For example, one process might alter shared resources which another process relied on, such as a variable stored in memory. When only one user was using the system, this would result in possibly wrong output - but with multiple users, this might mean that other users got to see information they were not meant to see.
To prevent this from happening, an operating system needed to enforce a set of policies that determined which privileges each process had. For example, the operating system might deny access to a certain variable by a certain process.
The first international conference on computer security in London in 1971 was primarily driven by the time-sharing industry and its customers.[42]
Time-sharing in the form of shell accounts has been considered a risk.[43]
Notable time-sharing systems
Significant early timesharing systems:[27]
- AT&T Bell Labs Unix (1971) → UC Berkeley BSD Unix (1977)
- SRI, Community Memory) → BCC 500 → MAXC at PARC
- MCP → HP 3000MPE
- Cambridge Multiple Access System was developed for the UNIX.
- 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.
- CompuServe, also branded as Compu-Serv, CIS.
- Compu-Time, Inc.,[27] on Honeywell 400/4000, started in 1968 in Ft Lauderdale, Florida, moved to Daytona Beach in 1970.
- CDC MACE, APEX → Kronos → NOS → NOS/VE
- Dartmouth Time Sharing System (DTSS) → GE Time-sharing → GEnie
- DEC TSS/8 → RSTS-11, RSX-11 → OpenVMS
- English Electric KDF9COTAN (Culham Online Task Activation Network)
- HP 2000 Time-Shared BASIC
- HP 3000 series
- IBM CALL/360, CALL/OS - using IBM System/360 Model 50
- VM/CMS
- TSS/360→ TSS/370
- GEORGE 3MOP (Multiple Online Programming)
- International Timesharing Corporation on dual CDC 3300 systems.[27]
- Linux: see how it evolved from MIT CTSS
- MIT Time-sharing System for the DEC PDP-1 → ITS
- McGill University MUSIC → IBM MUSIC/SP
- S/370, and successors.
- CDC SCOPE/HUSTLER System
- IBM 360 series; originally based on IBM's CP/CMS.
- CDC 3000series.
- Prime Computer PRIMOS
- RAND JOSS→ JOSS-2 → JOSS-3
- RCA TSOS → Univac / Unisys VMOS → VS/9
- Service in Informatics and Analysis (SIA), on CDC 6600 Kronos.
- System Development Corporation Time-sharing System, on the AN/FSQ-32.
- Stanford ORVYL and WYLBUR, on IBM S/360-67.
- SAIL → WAITS
- Automatic Data Processing(ADP), first commercial time-sharing system in Europe and first dual (fault tolerant) time-sharing system.
- Tone (TSO-like, for VS1), a non-IBM Time-sharing product, marketed by Tone Software Co; TSO required VS2.
- Tymshare SDS-940 → Tymcom X → Tymcom XX
- EXEC 8 → OS 1100 → OS 2200
- UC Berkeley CAL-TSS, on CDC 6400.
- CP-V → Honeywell CP-6
See also
- Cloud computing
- The Heralds of Resource Sharing, a 1972 film.
- History of CP/CMS, IBM's virtual machine operating system (CP) that supported time-sharing (CMS).
- IBM 7044used to simulate multiple virtual machines.
- IBM S/360 seriesmainframe to support virtual memory.
- Multiseat configuration, multiple users on a single personal computer.
- MIT famous for groundbreaking research in operating systems, artificial intelligence, and the theory of computation.
- BBNin 1964.
- Timeline of operating systems
- VAX (Virtual Address eXtension), a computer architecture and family of computers developed by DEC.
- Utility computing
- Virtual memory
- Time-sharing system evolution
References
- ^ IBM advertised, early 1960s, with a headline: "This man is sharing a $2 million computer"
- ^ "History of Operating Systems" (PDF).
- ^ "Ellis D. Kropotchev Silent Film - CHM Revolution". www.computerhistory.org. Retrieved 2023-05-26.
- ^ S2CID 30976386.
- ^ Backus, John, Digital Computers: Advanced Coding Techniques Archived 2022-08-06 at the Wayback Machine, MIT 1954, page 16-2. The first known description of computer time-sharing.
- ^ Bemer, Bob (March 1957). "Origins of Timesharing". bobbemer.com. Archived from the original on 2017-07-02. Retrieved June 24, 2016.
- ].
- ^ Bauer, W. F. (December 1958). Computer design from the programmer's viewpoint] (PDF). Eastern Joint Computer Conference. Archived from the original (PDF) on 2016-07-23.
One of the first descriptions of computer time-sharing.
- ^ "Computer Pioneers - Christopher Strachey". history.computer.org. Retrieved 2020-01-23.
What Strachey proposed in his concept of time-sharing was an arrangement that would preserve the direct contact between programmer and machine, while still achieving the economy of multiprogramming.
- ^ "Computer - Time-sharing and minicomputers". Encyclopedia Britannica. Retrieved 2020-01-23.
In 1959 Christopher Strachey in the United Kingdom and John McCarthy in the United States independently described something they called time-sharing.
- ^ Strachey, Christopher (1959-06-15). Time sharing in large fast computers. UNESCO Information Processing conference. Retrieved 30 May 2023.
- ISBN 978-0-19-286207-5.
- ISBN 978-0-262-03008-3. "To establish the context of the present work, it is informative to trace the development of time-sharing at MIT. Shortly after the first paper on time-shared computers by C. Strachey at the June 1959 UNESCO Information Processing conference, H.M. Teager and J. McCarthy delivered an unpublished paper "Time-Shared Program Testing" at the August 1959 ACM Meeting."
- ^ Brian Dear, Chapter 4 -- The Diagram, The Friendly Orange Glow, Pantheon Books, New York, 2017; pages 71-72 discuss the development of time-sharing and the University of Illinois loss of the patent.
- ^ "Reminiscences on the Theory of Time-Sharing". John McCarthy's Original Website. Retrieved 2020-01-23.
in 1960 'time-sharing' as a phrase was much in the air. It was, however, generally used in my sense rather than in John McCarthy's sense of a CTSS-like object.
- ^ a b c d Walden, David; Van Vleck, Tom, eds. (2011). "Compatible Time-Sharing System (1961-1973): Fiftieth Anniversary Commemorative Overview" (PDF). IEEE Computer Society. Retrieved February 20, 2022.
- ISBN 9780553070118.
When we started delivering our first commercial machines, our customers often found that the most difficult thing about having a computer was finding somebody who could run it. We couldn't produce all those technicians ourselves. Yet there was not a single university with a computer curriculum. So I went up to MIT in the mid-1950s and urged them to start training computer scientists. We made a gift of a large computer and the money to run it.
- S2CID 30631012. Retrieved October 3, 2022.
Corbato: No, that was one of the interesting aspects. One of the terms of IBM's donation for the use of the equipment was that we were not to charge for it. It was free all right.
- S2CID 16483923.
- ISBN 9780674970977
- PMID 5675464.
- ^ "TRANSCRIPTS OF 1974 National Computer Conference Pioneer Day Session". Dartmouth Time Sharing System. Dartmouth College. 1974.
- LCCN 72-1176.
- ^ IBM 2741 Communication Terminal (PDF). IBM. p. 12. Archived from the original (PDF) on 2017-03-16. Retrieved 2015-10-06.
- ^ Jeffrey R. Yost, Making IT Work: A History of the Computer Services Industry, 2017, ISBN 0262342197 p. 158
- ^ "Information Technology Corporate Histories Collection". Computer History Museum. Retrieved on 2013-11-29 from http://www.computerhistory.org/corphist/view.php?s=stories&id=136.
- ^ a b c d Auerbach Guide to Time Sharing (PDF). Auerbach Publishers, Inc. 1973. Retrieved 2013-11-29.
- ^ DEC Timesharing (1965), by Peter Clark, The DEC Professional, Volume 1, Number 1
- ^ Computerworld, June 11, 1975, p. 35
- ^ One Two-page IBM print ad was headlined "100 or more people can use IBM's new time-sharing computer at the same time." Originals were/are? on eBay
- ^ p.1425, Encyclopedia of Computer Science, Litton Educational Publishing, Inc.
- ^ https://groups.google.com/forum/#!topic/alt.folklore.computers/aE4TwORruB8 - "I worked for RapiData Timesharing for about a year circa 1969..."
- ^ someone else: "I worked there for almost 2 years 1977 to 1979." alt.folklore.computers/aE4TwORruB8/EdpKfFAlBncJ
- ^ "Stocks". Bloomberg.com. 2023-05-26. Retrieved 2023-05-26.
- ISBN 978-089529-1-677
- ^ Computerworld, Oct. 6, 1986, p.179, "Rapidata revenue was $11 million ... in 1986, down from ... ($31 million in 1982)."
- ^ Computerworld, Aug.25,1986, p.5, "National Data Corp. said it is close to reaching an agreement with a buyer of its Rapidata timesharing division. In May, National Data said it would close down ..."
- ^ National Data Corp became NDC-Health Corp in 2001 (bizjournals.com/atlanta/stories/2001/10/29/daily25.html)
- ^ As for a place in history, Rapidata is listed in 'The AUERBACH Guide to Time Sharing (1973)' http://bitsavers.informatik.uni-stuttgart.de/pdf/auerbach/GuideToTimesharing_Jan73.pdf
- ^ "Multics Commands and Active Functions (AG92-06)" (PDF). BitSavers. Honeywell Bull, Inc. February 1985. Archived from the original (PDF) on June 6, 2022. Retrieved January 10, 2021.
- ISBN 978-0-470-23399-3.
- OCLC 1011609244.[page needed]
- .
Most recent vulnerabilities are not directly exploitable remotely on most systems. This means that most systems are not at risk for remote attack from the Internet. Many of the vulnerabilities may be taken advantage of by someone with a regular shell account on the system.
- .
- ISBN 978-0901224002
- ^ "Time Sharing", James Miller. Retrieved 30 November 2013.
Further reading
- ISBN 0-89347-002-3. pp. 56–57.
- Fredkin, Edward (Nov 1963). "The Time Sharing of Computers" (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]
External links
- Alexander, Michael T. (May 1971). Time Sharing Supervisor Programs (Thesis). hdl:2027.42/79614.
- "The Computer Utility As A Marketplace For Computer Services", Robert Frankston's MIT Master's Thesis, 1973.
- "40 years of Multics, 1969-2009", an interview with Professor Fernando J. Corbató on the history of Multics and origins of time-sharing, 2009.
- "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", Revolution: The First 2000 Years of Computing, Computer History Museum Exhibition, January 2011.
→ derivation >> strong influence > some influence/precedence | ||
CTSS | ||
> IBM M44/44X | ||
>> CP-40/CMS → CP[-67]/CMS | → VM/ESA → z/VM
| |
→ VP/CSS | ||
> TSS/360
| ||
> TSO for MVT → for OS/VS2 → for MVS → ... → for z/OS | ||
>> MULTICS and most other time-sharing platforms |
- ^ Allen, Ruth; (U.S.), National Library of Medicine (1969). An Annotated Bibliography of Biomedical Computer Applications. 70: National Library of Medicine.
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