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Information about Time Sharing

''For other possible meanings, see Time share (disambiguation)
Time-sharing refers to sharing a computing resource among many users by multitasking.

Because early mainframes and minicomputers were extremely expensive, it was rarely possible to allow a single user exclusive access to the machine for interactive use. But because computers in interactive use often spend much of their time idly waiting for user input, it was suggested that multiple users could share a machine by using one user's idle time to service other users. Similarly, small slices of time spent waiting for disk, tape, or network input could be granted to other users.

Throughout the late 1960s and the 1970s, computer terminals were multiplexed onto large institutional mainframe computers (central computer systems), which in many implementations sequentially polled the terminals to see if there was any additional data or action requested by the computer user. Later technology in interconnections were interrupt driven, and some of these used parallel data transfer technologies like, for example, 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.

With the rise of microcomputing in the early 1980s, time-sharing faded into the background because the individual microprocessors were sufficiently inexpensive that a single person could have all the CPU time dedicated solely to their needs, even when idle.

The Internet has 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, websites operate primarily in bursts of activity followed by periods of idle time. This bursting nature permits the service to be used by many website customers at once, and none of them notice any delays in communications until the servers start to get very busy.

The Time-sharing Business

In the 1960s, several companies started providing time-sharing services as service bureaus. Early systems used Teletype K/ASR-33s or K/ASR-35s in ASCII environments, and an IBM teleprinter in EBCDIC environments. They would connect to the central computer by dial-up 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, and the IBM 360. Companies providing this service included Tymshare (founded in 1966), Dial Data (bought by Tymshare in 1968), and Bolt, Beranek, and Newman. By 1968, there were 32 such service bureaus serving the NIH alone.[1] The Auerbach Guide to Timesharing 1973 edition lists 125 different timesharing services using equipment from Burroughs, CDC, DEC, HP, Honeywell, IBM , RCA, Univac and XDS.

The Computer Utility

A great deal of thought was given in the 70's to centralized computer resources being offered as computing utilities, the same as the electrical or telephone utilities. Ted Nelson's original "Xanadu" hypertext repository was envisioned as such a service. It became clear as the computer industry grew that no such consolidation of computing resources would occur as timesharing systems. Some argue that the move through client-server computing to centralized server farms and virtualization presents a market for computing utilities again.

History

The concept was first described publicly in early 1957 by Bob Bemer as part of an article in Automatic Control Magazine. The first project to implement a time-sharing system was initiated by John McCarthy in late 1957, on a modified IBM 704, and later an additionally modified IBM 7090 computer. Although he left to work on Project MAC and other projects, one of the results of the project, known as the Compatible Time Sharing System or CTSS, was demonstrated in November, 1961. CTSS has a good claim to be the first time-sharing system and remained in use until 1973. The first commercially successful time-sharing system was the Dartmouth Time-Sharing System (DTSS) which was first implemented at Dartmouth College in 1964 and subsequently formed the basis of General Electric's computer bureau services. DTSS influenced the design of other early timesharing systems developed by Hewlett Packard, Control Data Corporation, UNIVAC and others (in addition to introducing the BASIC programming language).

Significant early timesharing systems:

''Also see: Time-sharing system evolution

Reference

Computer Utilities Time-sharing Systems
Time share (or timeshare) may refer to:
  • Timeshare, a form of shared vacation property ownership
  • Time Share, a comedy film set for release in 2008
  • Time-sharing, a way of sharing computer resources among many users

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In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running
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Mainframes (often colloquially referred to as Big Iron) are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, ERP, and financial transaction processing.
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Minicomputer (colloquially, mini) is a largely obsolete term for a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems (mainframe computers) and the smallest single-user systems (microcomputers or
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In computer science and computer programming, system time represents a computer system's notion of the passing of time. In this sense, time also includes the passing of days on the calendar.
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A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system. A computer terminal is an instance of a human-machine interface(HMI).
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Mainframes (often colloquially referred to as Big Iron) are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, ERP, and financial transaction processing.
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In computing, an interrupt is an asynchronous signal from hardware indicating the need for attention or a synchronous event in software indicating the need for a change in execution.
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IEEE-488 is a short-range, digital communications bus specification that has been in use for over 30 years. Originally created for use with automated test equipment, the standard is still in wide use for that purpose.
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desktop computer is a computer made for use on a desk in an office or home and is distinguished from portable computers such as laptops or PDAs. Desktop computers are also known as microcomputers.
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personal computer (PC) is a computer whose original sales price, size, and capabilities make it useful for individuals.

It is unknown who coined the phrase with the intent of a small affordable computing device but John W.
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CPU Time is the amount of time a computer program uses in processing on a CPU, often measured in clock ticks. It is used as a point of comparison for CPU usage of a program.

References

Thimmannagari, Chandra (2005-01-01).
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A service bureau is a company which provides computer services for a fee. The term is no longer widely used, except for payroll service bureaus.

If the services are computing facilities, not a specific business service, the service is now called utility computing.
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A teleprinter (teletypewriter, Teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical
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keyboard send and receive]]" while "ASR" stood for "automatic send and receive."

More expensive Teletype systems used photo readers that used light sensors to detect the presence or absence of punched holes in the tape.
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American Standard Code for Information Interchange (ASCII), generally pronounced ask-ee IPA: /ˈæski/ ( [1] ), is a character encoding based on the English alphabet.
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International Business Machines Corporation

Public (NYSE:  IBM )
Founded 1889, incorporated 1911
Headquarters Armonk, New York, USA

Key people Samuel J.
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Extended Binary Coded Decimal Interchange Code (EBCDIC) is an 8-bit character encoding (code page) used on IBM mainframe operating systems, like z/OS, OS/390, VM and VSE, as well as IBM minicomputer operating systems like OS/400 and i5/OS (see also Binary Coded Decimal).
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hot Dial-up access is a form of Internet access via telephone line. The client uses a modem connected to a computer and a telephone line to dial into an Internet service provider's (ISP) node to establish a modem-to-modem link, which is then routed to the Internet.
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acoustic coupler has the following meanings:
  1. An interface device for coupling electrical signals by acoustical means--usually into and out of a telephone instrument.
  2. A terminal device used to link data terminals and radio sets with the telephone network.

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Modem (from modulate and demodulate) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information.
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The SDS 940 was Scientific Data Systems' (SDS) first machine designed to support time sharing directly, and was based on the SDS 930's 24-bit CPU built primarily of integrated circuits.
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The PDP-10 was a computer manufactured by Digital Equipment Corporation (DEC) from the late 1960s on; the name stands for "Programmed Data Processor model 10". It was the machine that made time-sharing common; it looms large in hacker folklore because of its adoption in the 1970s
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System/360 Model 65 operator's console, with register value lamps and toggle switches (middle of picture) and "emergency pull" switch (upper right).]] The IBM System/360 (S/360) is a mainframe computer system family announced by IBM on April 7, 1964.
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Tymnet was an international data communications network headquartered in San Jose, California that utilized virtual call packet switched technology and used X.25, SNA/SDLC, ASCII and BSC interfaces to connect host computers (servers) at thousands of large companies, educational
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BBN Technologies (originally Bolt Beranek and Newman) is a high-technology company that provides research and development services. BBN is based next to Fresh Pond in Cambridge, Massachusetts, USA.
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National Institutes of Health (NIH) is an agency of the United States Department of Health and Human Services and is the primary agency of the United States government responsible for biomedical research.
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The Burroughs Corporation began in 1886 as the American Arithmometer Company in St. Louis, Missouri selling an adding machine invented by William Seward Burroughs.
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Control Data Corporation (CDC), was one of the pioneering supercomputer firms. For most of the 1960s they built the fastest computers in the world by far, only losing that crown in the 1970s to what was effectively a spinoff.
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Digital Equipment Corporation was a pioneering American company in the computer industry. It is often referred to within the computing industry as DEC. (This acronym was frequently officially used by Digital itself,[1] but the official name was always DIGITAL.
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