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Time-sharing

November 24, 2023

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.

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 edit

Batch processing edit

Main article: 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, run times dropped, and soon the time taken to start up the next program became a concern. Newer batch processing software and methodologies, including batch operating systems such as IBSYS (1960), decreased these "dead periods" by queuing up programs ready to run.[2]

Comparatively inexpensive card punch or paper tape writers were used by programmers to write their programs "offline". Programs were submitted to the operations team, which scheduled them to be run. Output (generally printed) was returned to the programmer. The complete process might take days, during which time the programmer might never see the computer. Stanford students made a short film humorously critiquing this situation.[3]

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 edit

 
Unix time-sharing at the University of Wisconsin, 1978

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 multiprogramming without multiple user sessions.[4] In 1984 Christopher Strachey wrote he considered the change in the meaning of the term time-sharing a source of confusion and not what he meant when he wrote his paper in 1959.[14]

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.[15]

The first interactive, general-purpose time-sharing system usable for software development, Compatible Time-Sharing System, was initiated by John McCarthy at MIT writing a memo in 1959.[16] Fernando J. Corbató led the development of the system, a prototype of which had been produced and tested by November 1961.[17] Philip M. Morse arranged for IBM to provide a series of their mainframe computers starting with the IBM 704 and then the IBM 709 product line IBM 7090 and IBM 7094.[17] IBM loaned those mainframes at no cost to MIT along with the staff to operate them and also provided hardware modifications mostly in the form of RPQs as prior customers had already commissioned the modifications.[18][17] There were certain stipulations that governed MIT's use of the loaned IBM hardware. MIT could not charge for use of CTSS.[19] MIT could only use the IBM computers for eight hours a day; another eight hours were available for other colleges and universities; IBM could use their computers for the remaining eight hours, although there were some exceptions. In 1963 a second deployment of CTSS was installed on an IBM 7094 that MIT has purchased using ARPA money. This was used to support Multics development at Project MAC.[17]

JOSS began time-sharing service in January 1964.[20] Dartmouth Time Sharing System (DTSS) began service in March 1964.[21]

Development edit

Throughout the late 1960s and the 1970s, computer terminals were multiplexed onto large institutional mainframe computers (centralized computing systems), which in many implementations sequentially polled the terminals to see whether any additional data was available or action was requested by the computer user. Later technology in interconnections were interrupt driven, and some of these used parallel data transfer technologies such as the IEEE 488 standard. Generally, computer terminals were utilized on college properties in much the same places as desktop computers or personal computers are found today. In the earliest days of personal computers, many were in fact used as particularly smart terminals for time-sharing systems.

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".[22] Conversely, timesharing users thought that their terminal was the computer.[23] It was an efficient way to share a large computer. As of 1972 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.[24] 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 edit

Genesis

In the 1960s, several companies started providing time-sharing services as service bureaus. Early systems used Teletype Model 33 KSR or ASR or Teletype Model 35 KSR or ASR machines in ASCII environments, and IBM Selectric typewriter-based terminals (especially the IBM 2741) with two different seven-bit codes.[25] They would connect to the central computer by dial-up Bell 103A modem or acoustically coupled modems operating at 10–15 characters per second. Later terminals and modems supported 30–120 characters per second. The time-sharing system would provide a complete operating environment, including a variety of programming language processors, various software packages, file storage, bulk printing, and off-line storage. Users were charged rent for the terminal, a charge for hours of connect time, a charge for seconds of CPU time, and a charge for kilobyte-months of disk storage.

Common systems used for time-sharing included the SDS 940, the PDP-10, the IBM 360, and the GE-600 series. Companies providing this service included GE's GEISCO, the IBM subsidiary The Service Bureau Corporation, Tymshare (founded in 1966), National CSS (founded in 1967 and bought by Dun & Bradstreet in 1979), Dial Data (bought by Tymshare in 1968), AL/COM, Bolt, Beranek, and Newman (BBN) and Time Sharing Ltd. in the UK.[26] By 1968, there were 32 such service bureaus serving the US National Institutes of Health (NIH) alone.[27] The Auerbach Guide to Timesharing (1973) lists 125 different timesharing services using equipment from Burroughs, CDC, DEC, HP, Honeywell, IBM, RCA, Univac, and XDS.[28][29]

Rise and fall edit

In 1975, acting president of Prime Computer Ben F. Robelen told stockholders that "The biggest end-user market currently is time-sharing."[30] For DEC, for a while the second largest computer company (after IBM), this was also true: Their PDP-10 and IBM's 360/67[31] were widely used[32] 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 edit

Although many time-sharing services simply closed, Rapidata[33][34] held on, and became part of National Data Corporation.[35] It was still of sufficient interest in 1982 to be the focus of "A User's Guide to Statistics Programs: The Rapidata Timesharing System".[36] Even as revenue fell by 66%[37] and National Data subsequently developed its own problems, attempts were made to keep this timesharing business going.[38][39][40]

UK edit
  • Time Sharing Limited (TSL, 1969-1974) - launched using DEC systems. PERT was one of its popular offerings. TSL was acquired by ADP in 1974.
  • OLS Computer Services (UK) Limited (1975-1980) - using HP & DEC systems.

The computer utility edit

Beginning in 1964, the Multics operating system[41] was designed as a computing utility, modeled on the electrical or telephone utilities. In the 1970s, Ted Nelson's original "Xanadu" hypertext repository was envisioned as such a service.

Security edit

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.[42] 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.[citation needed]

Time-sharing in the form of shell accounts has been considered a risk.[43]

Notable time-sharing systems edit

See also: Time-sharing system evolution

Significant early timesharing systems:[28]

See also edit

References edit

  1. ^ IBM advertised, early 1960s, with a headline: "This man is sharing a $2 million computer"
  2. ^ "History of Operating Systems" (PDF).
  3. ^ "Ellis D. Kropotchev Silent Film - CHM Revolution". www.computerhistory.org. Retrieved 2023-05-26.
  4. ^ a b c d Lee, J.A.N.; Rosin, Robert F (1992). "Time-Sharing at MIT". IEEE Annals of the History of Computing. 14 (1): 16. doi:10.1109/85.145316. S2CID 30976386. Retrieved October 3, 2022.
  5. ^ Backus, John, Digital Computers: Advanced Coding Techniques 2022-08-06 at the Wayback Machine, MIT 1954, page 16-2. The first known description of computer time-sharing.
  6. ^ Bemer, Bob (March 1957). . bobbemer.com. Archived from the original on 2017-07-02. Retrieved June 24, 2016.
  7. ^ Middleburg, C.A. (2010). "Searching Publications on Operating Systems". arXiv:1003.5525 [cs.OS].
  8. ^ Bauer, W. F. (December 1958). (PDF). Eastern Joint Computer Conference. Archived from the original (PDF) on 2016-07-23. One of the first descriptions of computer time-sharing.
  9. ^ "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.
  10. ^ "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.
  11. ^ Strachey, Christopher (1959-06-15). Time sharing in large fast computers. UNESCO Information Processing conference. Retrieved 30 May 2023.
  12. ^ Gillies, James M.; Gillies, James; Gillies, James; Cailliau, Robert (2000). How the Web was Born: The Story of the World Wide Web. Oxford University Press. p. 13. ISBN 978-0-19-286207-5.
  13. ^ F. J. Corbató, et al., The Compatible Time-Sharing System A Programmer's Guide (MIT Press, 1963) 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."
  14. ^ Lee, J.A.N.; Rosin, Robert F (1992). "Time-Sharing at MIT". IEEE Annals of the History of Computing. 14 (1): 16. doi:10.1109/85.145316. S2CID 30976386. Retrieved October 3, 2022. I did not envisage the sort of console system which is now so confusingly called time-sharing.
  15. ^ 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.
  16. ^ "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.
  17. ^ 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.
  18. ^ Watson Jr., Thomas J. (1990). Father, Son, and Co.: My Life at IBM and Beyond. New York: Bantam Books. p. 244-245. 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.
  19. ^ Lee, J.A.N.; Rosin, Robert F (1992). "Time-Sharing at MIT". IEEE Annals of the History of Computing. 14 (1): 18. doi:10.1109/85.145317. 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.
  20. ^ J. C. Shaw (1964). "JOSS: a designer's view of an experimental on-line computing system". Proceeding AFIPS '64 (Fall, part I) Proceedings of the October 27-29, 1964, fall joint computer conference, part I. pp. 455–464. doi:10.1145/1464052.1464093. ISBN 9781450378895. S2CID 16483923.
  21. ^ Rankin, Joy Lisi (2018), A People's History of Computing in the United States, Cambridge, Massachusetts: Harvard University Press, ISBN 9780674970977
  22. ^ Kemeny, John G.; Kurtz, Thomas E. (11 October 1968). "Dartmouth Time-Sharing". Science. 162 (3850): 223–228. Bibcode:1968Sci...162..223K. doi:10.1126/science.162.3850.223. PMID 5675464.
  23. ^ "TRANSCRIPTS OF 1974 National Computer Conference Pioneer Day Session". Dartmouth Time Sharing System. Dartmouth College. 1974.
  24. ^ Kemeny, John G. (1972). Man and the Computer. New York: Charles Scribner's Sons. pp. 32–37, 41–42. ISBN 9780684130095. LCCN 72-1176.
  25. ^ (PDF). IBM. p. 12. Archived from the original (PDF) on 2017-03-16. Retrieved 2015-10-06.
  26. ^ Jeffrey R. Yost, Making IT Work: A History of the Computer Services Industry, 2017, ISBN 0262342197 p. 158
  27. ^ "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.
  28. ^ a b c d Auerbach Guide to Time Sharing (PDF). Auerbach Publishers, Inc. 1973. Retrieved 2013-11-29.
  29. ^ DEC Timesharing (1965), by Peter Clark, The DEC Professional, Volume 1, Number 1
  30. ^ Computerworld, June 11, 1975, p. 35
  31. ^ 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
  32. ^ p.1425, Encyclopedia of Computer Science, Litton Educational Publishing, Inc.
  33. ^ https://groups.google.com/forum/#!topic/alt.folklore.computers/aE4TwORruB8 - "I worked for RapiData Timesharing for about a year circa 1969..."
  34. ^ someone else: "I worked there for almost 2 years 1977 to 1979." alt.folklore.computers/aE4TwORruB8/EdpKfFAlBncJ
  35. ^ "Stocks". Bloomberg.com. 2023-05-26. Retrieved 2023-05-26.
  36. ^ Bruce Bosworth, ISBN 978-089529-1-677
  37. ^ Computerworld, Oct. 6, 1986, p.179, "Rapidata revenue was $11 million ... in 1986, down from ... ($31 million in 1982)."
  38. ^ 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 ..."
  39. ^ National Data Corp became NDC-Health Corp in 2001 (bizjournals.com/atlanta/stories/2001/10/29/daily25.html)
  40. ^ 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
  41. ^ (PDF). BitSavers. Honeywell Bull, Inc. February 1985. Archived from the original (PDF) on June 6, 2022. Retrieved January 10, 2021.
  42. ^ Silberschatz, Abraham; Galvin, Peter; Gagne, Greg (2010). Operating system concepts (8th ed.). Hoboken, N.J.: Wiley & Sons. p. 591. ISBN 978-0-470-23399-3.
  43. ^ Bob Toxen (May–June 2007), "The Seven Deadly Sins of Linux Security", Queue, ACM, New York, USA, 5 (4): 38–47, doi:10.1145/1255421.1255423, ISSN 1542-7730, 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.
  44. ^ "A Brief Description of Privacy Measures in the RUSH Time-Sharing System", J.D. Babcock, AFIPS Conference Proceedings, Spring Joint Computer Conference, Vol. 30, 1967, pp. 301-302.
  45. ^ Hartley, D. F. (1968), The Cambridge multiple-access system: user's reference manual, Cambridge: Cambridge Univ. Press, ISBN 978-0901224002
  46. ^ "Time Sharing", James Miller. Retrieved 30 November 2013.

Further reading edit

  • Nelson, Theodor (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.
  • 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 edit

  • "Time Sharing Supervisor Programs", notes comparing the supervisor programs of CP-67, TSS/360, the Michigan Terminal System (MTS), and Multics by Michael T. Alexander, Advanced Topics in Systems Programming (1970, revised 1971), University of Michigan Engineering Summer Conference.
  • "The Computer Utility As A Marketplace For Computer Services", Robert Frankston's MIT Master's Thesis, 1973.
  • , 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.
CP/CMS family relationships
→ derivation     >> strong influence     > some influence/precedence
 CTSS 
> IBM M44/44X
>> CP-40/CMS → CP[-67]/CMS  → VM/370 → VM/SE versions → VM/SP versions → VM/XA versions → 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
  1. ^ Allen, Ruth; (U.S.), National Library of Medicine (1969). An Annotated Bibliography of Biomedical Computer Applications. 70: National Library of Medicine.{{cite book}}: CS1 maint: location (link)

November 24, 2023
time, sharing, this, article, about, computing, term, type, property, ownership, timeshare, time, sharing, communications, media, time, division, multiple, access, computing, time, sharing, sharing, computing, resource, among, many, tasks, users, enables, mult. 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 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 Contents 1 History 1 1 Batch processing 1 2 Time sharing 1 3 Development 1 4 Time sharing business 1 4 1 Rise and fall 1 4 1 1 Rapidata as an example 1 4 1 2 UK 1 5 The computer utility 1 6 Security 2 Notable time sharing systems 3 See also 4 References 5 Further reading 6 External linksHistory editBatch processing edit Main article 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 run times dropped and soon the time taken to start up the next program became a concern Newer batch processing software and methodologies including batch operating systems such as IBSYS 1960 decreased these dead periods by queuing up programs ready to run 2 Comparatively inexpensive card punch or paper tape writers were used by programmers to write their programs offline Programs were submitted to the operations team which scheduled them to be run Output generally printed was returned to the programmer The complete process might take days during which time the programmer might never see the computer Stanford students made a short film humorously critiquing this situation 3 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 edit nbsp Unix time sharing at the University of Wisconsin 1978The 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 multiprogramming without multiple user sessions 4 In 1984 Christopher Strachey wrote he considered the change in the meaning of the term time sharing a source of confusion and not what he meant when he wrote his paper in 1959 14 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 15 The first interactive general purpose time sharing system usable for software development Compatible Time Sharing System was initiated by John McCarthy at MIT writing a memo in 1959 16 Fernando J Corbato led the development of the system a prototype of which had been produced and tested by November 1961 17 Philip M Morse arranged for IBM to provide a series of their mainframe computers starting with the IBM 704 and then the IBM 709 product line IBM 7090 and IBM 7094 17 IBM loaned those mainframes at no cost to MIT along with the staff to operate them and also provided hardware modifications mostly in the form of RPQs as prior customers had already commissioned the modifications 18 17 There were certain stipulations that governed MIT s use of the loaned IBM hardware MIT could not charge for use of CTSS 19 MIT could only use the IBM computers for eight hours a day another eight hours were available for other colleges and universities IBM could use their computers for the remaining eight hours although there were some exceptions In 1963 a second deployment of CTSS was installed on an IBM 7094 that MIT has purchased using ARPA money This was used to support Multics development at Project MAC 17 JOSS began time sharing service in January 1964 20 Dartmouth Time Sharing System DTSS began service in March 1964 21 Development edit Throughout the late 1960s and the 1970s computer terminals were multiplexed onto large institutional mainframe computers centralized computing systems which in many implementations sequentially polled the terminals to see whether any additional data was available or action was requested by the computer user Later technology in interconnections were interrupt driven and some of these used parallel data transfer technologies such as the IEEE 488 standard Generally computer terminals were utilized on college properties in much the same places as desktop computers or personal computers are found today In the earliest days of personal computers many were in fact used as particularly smart terminals for time sharing systems 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 22 Conversely timesharing users thought that their terminal was the computer 23 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 24 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 edit GenesisIn the 1960s several companies started providing time sharing services as service bureaus Early systems used Teletype Model 33 KSR or ASR or Teletype Model 35 KSR or ASR machines in ASCII environments and IBM Selectric typewriter based terminals especially the IBM 2741 with two different seven bit codes 25 They would connect to the central computer by dial up Bell 103A modem or acoustically coupled modems operating at 10 15 characters per second Later terminals and modems supported 30 120 characters per second The time sharing system would provide a complete operating environment including a variety of programming language processors various software packages file storage bulk printing and off line storage Users were charged rent for the terminal a charge for hours of connect time a charge for seconds of CPU time and a charge for kilobyte months of disk storage Common systems used for time sharing included the SDS 940 the PDP 10 the IBM 360 and the GE 600 series Companies providing this service included GE s GEISCO the IBM subsidiary The Service Bureau Corporation Tymshare founded in 1966 National CSS founded in 1967 and bought by Dun amp Bradstreet in 1979 Dial Data bought by Tymshare in 1968 AL COM Bolt Beranek and Newman BBN and Time Sharing Ltd in the UK 26 By 1968 there were 32 such service bureaus serving the US National Institutes of Health NIH alone 27 The Auerbach Guide to Timesharing 1973 lists 125 different timesharing services using equipment from Burroughs CDC DEC HP Honeywell IBM RCA Univac and XDS 28 29 Rise and fall edit In 1975 acting president of Prime Computer Ben F Robelen told stockholders that The biggest end user market currently is time sharing 30 For DEC for a while the second largest computer company after IBM this was also true Their PDP 10 and IBM s 360 67 31 were widely used 32 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 edit Although many time sharing services simply closed Rapidata 33 34 held on and became part of National Data Corporation 35 It was still of sufficient interest in 1982 to be the focus of A User s Guide to Statistics Programs The Rapidata Timesharing System 36 Even as revenue fell by 66 37 and National Data subsequently developed its own problems attempts were made to keep this timesharing business going 38 39 40 UK edit Time Sharing Limited TSL 1969 1974 launched using DEC systems PERT was one of its popular offerings TSL was acquired by ADP in 1974 OLS Computer Services UK Limited 1975 1980 using HP amp DEC systems The computer utility edit Beginning in 1964 the Multics operating system 41 was designed as a computing utility modeled on the electrical or telephone utilities In the 1970s Ted Nelson s original Xanadu hypertext repository was envisioned as such a service Security edit 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 42 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 citation needed Time sharing in the form of shell accounts has been considered a risk 43 Notable time sharing systems editSee also Time sharing system evolution Significant early timesharing systems 28 Allen Babcock RUSH Remote Users of Shared Hardware Time sharing System on IBM S 360 hardware 1966 44 Tymshare AT amp T Bell Labs Unix 1971 UC Berkeley BSD Unix 1977 BBN PDP 1 Time sharing System Massachusetts General Hospital PDP 1D MUMPS BBN TENEX DEC TOPS 20 Foonly FOONEX MAXC OS at PARC Stanford Low Overhead TimeSharing LOTS which ran TOPS 20 Berkeley Timesharing System at UC Berkeley Project Genie Scientific Data Systems SDS 940 Tymshare BBN SRI Community Memory BCC 500 MAXC at PARC Burroughs Time sharing MCP HP 3000 MPE Cambridge Multiple Access System was developed for the Titan the prototype Atlas 2 computer built by Ferranti for the University of Cambridge 45 This was the first time sharing system developed outside the United States and which influenced the later development of 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 amp P Communications and Processing in August 1994 CompuServe also branded as Compu Serv CIS Compu Time Inc 28 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 PDP 6 Time sharing Monitor TOPS 10 BBN TENEX DEC TOPS 20 DEC TSS 8 RSTS 11 RSX 11 OpenVMS English Electric KDF9 COTAN Culham Online Task Activation Network HP 2000 Time Shared BASIC HP 3000 series IBM CALL 360 CALL OS using IBM System 360 Model 50 IBM CP 40 CP 67 CP 370 CP CMS VM CMS IBM TSO for OS MVT for OS VS2 for MVS for z OS IBM TSS 360 TSS 370 ICT 1900 series GEORGE 3 MOP Multiple Online Programming International Timesharing Corporation on dual CDC 3300 systems 28 Linux see how it evolved from MIT CTSS MIT CTSS MULTICS MIT GE Bell Labs Unix Linux MIT Time sharing System for the DEC PDP 1 ITS McGill University MUSIC IBM MUSIC SP Michigan Terminal System on the IBM S 360 67 S 370 and successors Michigan State University CDC SCOPE HUSTLER System National CSS VP CSS on IBM 360 series originally based on IBM s CP CMS Oregon State University OS 3 on CDC 3000 series 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 Stanford PDP 1 Time sharing System SAIL WAITS Time Sharing Ltd TSL 46 on DEC PDP 10 systems 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 Unisys UNIVAC 1108 EXEC 8 OS 1100 OS 2200 UNIX see how it evolved from MIT CTSS UC Berkeley CAL TSS on CDC 6400 XDS UTS CP V Honeywell CP 6See also editCloud 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 M44 44X an experimental computer system based on an IBM 7044 used to simulate multiple virtual machines IBM System 360 Model 67 the only IBM S 360 series mainframe to support virtual memory Multiseat configuration multiple users on a single personal computer Project MAC a DARPA funded project at MIT famous for groundbreaking research in operating systems artificial intelligence and the theory of computation TELCOMP an interactive conversational programming language based on JOSS developed by BBN in 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 evolutionReferences edit 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 a b c d Lee J A N Rosin Robert F 1992 Time Sharing at MIT IEEE Annals of the History of Computing 14 1 16 doi 10 1109 85 145316 S2CID 30976386 Retrieved October 3 2022 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 Middleburg C A 2010 Searching Publications on Operating Systems arXiv 1003 5525 cs OS 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 Gillies James M Gillies James Gillies James Cailliau Robert 2000 How the Web was Born The Story of the World Wide Web Oxford University Press p 13 ISBN 978 0 19 286207 5 F J Corbato et al The Compatible Time Sharing System A Programmer s Guide MIT Press 1963 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 Lee J A N Rosin Robert F 1992 Time Sharing at MIT IEEE Annals of the History of Computing 14 1 16 doi 10 1109 85 145316 S2CID 30976386 Retrieved October 3 2022 I did not envisage the sort of console system which is now so confusingly called time sharing 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 Watson Jr Thomas J 1990 Father Son and Co My Life at IBM and Beyond New York Bantam Books p 244 245 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 Lee J A N Rosin Robert F 1992 Time Sharing at MIT IEEE Annals of the History of Computing 14 1 18 doi 10 1109 85 145317 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 J C Shaw 1964 JOSS a designer s view of an experimental on line computing system Proceeding AFIPS 64 Fall part I Proceedings of the October 27 29 1964 fall joint computer conference part I pp 455 464 doi 10 1145 1464052 1464093 ISBN 9781450378895 S2CID 16483923 Rankin Joy Lisi 2018 A People s History of Computing in the United States Cambridge Massachusetts Harvard University Press ISBN 9780674970977 Kemeny John G Kurtz Thomas E 11 October 1968 Dartmouth Time Sharing Science 162 3850 223 228 Bibcode 1968Sci 162 223K doi 10 1126 science 162 3850 223 PMID 5675464 TRANSCRIPTS OF 1974 National Computer Conference Pioneer Day Session Dartmouth Time Sharing System Dartmouth College 1974 Kemeny John G 1972 Man and the Computer New York Charles Scribner s Sons pp 32 37 41 42 ISBN 9780684130095 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 amp 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 Bruce Bosworth 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 Silberschatz Abraham Galvin Peter Gagne Greg 2010 Operating system concepts 8th ed Hoboken N J Wiley amp Sons p 591 ISBN 978 0 470 23399 3 Bob Toxen May June 2007 The Seven Deadly Sins of Linux Security Queue ACM New York USA 5 4 38 47 doi 10 1145 1255421 1255423 ISSN 1542 7730 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 A Brief Description of Privacy Measures in the RUSH Time Sharing System J D Babcock AFIPS Conference Proceedings Spring Joint Computer Conference Vol 30 1967 pp 301 302 Hartley D F 1968 The Cambridge multiple access system user s reference manual Cambridge Cambridge Univ Press ISBN 978 0901224002 Time Sharing James Miller Retrieved 30 November 2013 Further reading editNelson Theodor 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 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 edit Time Sharing Supervisor Programs notes comparing the supervisor programs of CP 67 TSS 360 the Michigan Terminal System MTS and Multics by Michael T Alexander Advanced Topics in Systems Programming 1970 revised 1971 University of Michigan Engineering Summer Conference 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 Corbato 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 CP CMS family relationshipsvte derivation gt gt strong influence gt some influence precedence CTSS gt IBM M44 44X gt gt CP 40 CMS CP 67 CMS VM 370 VM SE versions VM SP versions VM XA versions VM ESA z VM VP CSS gt TSS 360 gt TSO for MVT for OS VS2 for MVS for z OS gt gt 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 a href Template Cite book html title Template Cite book cite book a CS1 maint location link Retrieved from https en wikipedia org w index php title Time sharing amp oldid 1185206223, wikipedia, wiki, book, books, library,

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