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Twistor Memory
Twistor memory is a form of computer memory formed by wrapping magnetic tape around a current-carrying wire. Operationally, twistor was very similar to core memory. Twistor could also be used to make ROM memories, including a re-programmable form known as piggyback twistor. Both forms were able to be manufactured using automated processes, which was expected to lead to much lower production costs than core-based systems. Introduced by Bell Labs in 1957, the first commercial use was in their 1ESS switch which went into operation in 1965. Twistor was used only briefly in the late 1960s and early 1970s, when semiconductor memory devices replaced almost all earlier memory systems. The basic ideas behind twistor also led to the development of bubble memory, although this had a similarly short commercial lifespan. Core memory Construction In core memory, small ring-shaped magnets - the cores - are threaded by two crossed wires, ''X'' and ''Y'', to make a matrix known as a ''plane'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Memory
In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and digital electronic devices. The term ''memory'' is often synonymous with the term ''primary storage'' or '' main memory''. An archaic synonym for memory is store. Computer memory operates at a high speed compared to storage that is slower but less expensive and higher in capacity. Besides storing opened programs, computer memory serves as disk cache and write buffer to improve both reading and writing performance. Operating systems borrow RAM capacity for caching so long as not needed by running software. If needed, contents of the computer memory can be transferred to storage; a common way of doing this is through a memory management technique called ''virtual memory''. Modern memory is implemented as semiconductor memory, where data is stored within memory cells built from MOS transistors and other components on an integrated c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PET Film (biaxially Oriented)
BoPET (biaxially-oriented polyethylene terephthalate) is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties, and electrical insulation. A variety of companies manufacture boPET and other polyester films under different brand names. In the UK and US, the best-known trade names are Mylar, Melinex, and Hostaphan. History BoPET film was developed in the mid-1950s,Izard, Emmette Farr"Production of polyethylene terephthalate" U.S. patent no. 2,534,028 (filed: 1948 May 13; issued: 1950 December 12). originally by DuPont, Imperial Chemical Industries (ICI), and Hoechst. In 1955 Eastman Kodak used Mylar as a support for photographic film and called it "ESTAR Base". The very thin and tough film allowed reels to be exposed on long-range U-2 reconnaissance flights. In 1964, NASA launched Echo II, a diameter balloon constructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communications In Colombia
Since being liberalized in 1991, the Colombian telecommunications sector has added new services, expanded coverage, improved efficiency, and lowered costs. The sector has had the second largest (after energy) investment in infrastructure (54 percent) since 1997. However, the economic downturn between 1999 and 2002 adversely affected telecommunications. During this period, Colombia's telecommunications industry lost US$2 billion despite a profit of US$1 billion in local service. In June 2003, the government liquidated the state-owned and heavily indebted National Telecommunications Company (Empresa Nacional de Telecomunicaciones—Telecom) and replaced it with Colombia Telecomunicaciones (Colombia Telecom). The measure enabled the industry to expand rapidly, and in 2004 it constituted 2.8 percent of gross domestic product (GDP). Telefónica of Spain acquired 50 percent plus one share of the company in 2006. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communications In Mexico
Mass media in Mexico are regulated by the Secretariat of Communication and Transportation (''Secretaría de Comunicaciones y Transportes or SCT''), a federal executive cabinet ministry and by the Federal Telecommunications Institute (''Instituto Federal de Telecomunicaciones or IFT''). Mexico's communication services market is among the largest in Latin America, liberalized in the 1990s, with the landmark privatization of Teléfonos de México (Telmex), a previously state-owned monopoly. Since then, new operators have entered the market, but Telmex remains the dominant player. Regulation Founded on 13 May 1891, as the Secretariat of Communications and Public Works, the SCT is divided into three subsecretariats: the Subsecretariat of Infrastructure, the Subsecretariat of Communications and the Subsecretariat of Transportation. The SCT has ceded many of its regulatory functions to the Federal Telecommunications Institute. Radio and television Usage of radio, television and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Switchboard
A telephone switchboard was a device used to connect circuits of telephones to establish telephone calls between users or other switchboards, throughout the 20th century. The switchboard was an essential component of a manual telephone exchange, and was operated by switchboard operators who used electrical cords or switches to establish the connections. The electromechanical automatic telephone exchange, invented by Almon Strowger in 1888, gradually replaced manual switchboards in central telephone exchanges around the world. In 1919, the Bell System in Canada also adopted automatic switching as its future technology, after years of reliance on manual systems. Nevertheless, many manual branch exchanges remained operational into the second half of the 20th century in many enterprises. Later electronic devices and computer technology gave the operator access to an abundance of features. A private branch exchange (PBX) in a business usually has an attendant console, or an auto-atten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traffic Service Position System
The Traffic Service Position System (TSPS) was developed by Bell Labs in Columbus, Ohio to replace traditional cord switchboards. The first TSPS was deployed in 1969 and used the Stored Program Control-1A CPU, "Piggyback" twistor memory (a proprietary technology developed by Bell Labs similar to core memory) and Insulated Gate Field Effect Transistor solid state memory devices similar to dynamic random access memory. Features The TSPS system utilized special analog trunks that originated at Class 5 end office circuit switch systems and Class 4 toll access circuit switch systems that were connected to Class 3 primary toll circuit switch systems such as the 4A-ETS/PBC and 4ESS switch systems. The TSPS system did not perform switching between the originating end office switch and the toll switch for the subscriber voice path. The TSPS system included the "Remote Trunking Arrangement" (RTA) feature that consolidated the trunk connection at the originating switch and provided a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4ESS Switch
The No. 4 Electronic Switching System (4ESS) is a class 4 telephone electronic switching system that was the first digital electronic toll switch introduced by Western Electric for long-distance switching. It was introduced in Chicago in January 1976, to replace the 4A crossbar switch. The last of the 145 systems in the AT&T network was installed in 1999 in Atlanta. Approximately half of the switches were manufactured in Lisle, Illinois, and the other half in Oklahoma City, Oklahoma. At the time of the Bell System divestiture, most of the 4ESS switches became assets of AT&T as part of the long-distance network, while others remained in the RBOC networks. Over 140 4ESS switches remained in service in the United States in 2007. System architecture The 4ESS Switch is often considered as a switching network and its controlling processor. The major functional equipment areas include: * 1B processor, the 4ESS primary controlling processor * 3B computer and associated attached proc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Switch
telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers. In historical perspective, telecommunication terms have been used with different semantics over time. The term ''telephone exchange'' is often used synonymously with ''central office'', a Bell System term. Often, a ''central office'' is defined as a building used to house the inside plant equipment of potentially several telephone exchanges, each serving a certain geographical area. Such an area has also been referred to as the exchange or exchange area. In North America, a central office location may also be identified as a ''wire center'', designating a facility to which a telephone is connected and obtains dial tone. For business and billing purposes, telecommunication carriers defin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Telephone & Telegraph
AT&T Corporation, originally the American Telephone and Telegraph Company, is the subsidiary of AT&T Inc. that provides voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agencies. During the Bell System's long history, AT&T was at times the world's largest telephone company, the world's largest cable television operator, and a regulated monopoly. At its peak in the 1950s and 1960s, it employed one million people and its revenue ranged between US$3 billion in 1950 ($ in present-day terms) and $12 billion in 1966 ($ in present-day terms). In 2005, AT&T was purchased by Baby Bell and former subsidiary SBC Communications for more than $16 billion ($ in present-day terms). SBC then changed its name to AT&T Inc. Today, AT&T Corporation continues to exist as the long distance subsidiary of AT&T Inc., and its name occasionally shows up in AT&T press releases. Buildings with AT&T logo * AT&T Huro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell System
The Bell System was a system of telecommunication companies, led by the Bell Telephone Company and later by the American Telephone and Telegraph Company (AT&T), that dominated the telephone services industry in North America for over one hundred years from its creation in 1877 until its antitrust breakup in 1983. The system of companies was often colloquially called Ma Bell (as in "Mother Bell"), as it held a vertical monopoly over telecommunication products and services in most areas of the United States and Canada. At the time of the breakup of the Bell System in the early 1980s, it had assets of $150 billion (equivalent to $ billion in ) and employed over one million people. Ever since the 1910s, American antitrust regulators had been observing and accusing the Bell System of abusing its monopoly power, and had brought legal action multiple times over the decades, until in 1974 the Antitrust Division of the U.S. Department of Justice brought a lawsuit against Be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LIM-49 Nike Zeus
Nike Zeus was an anti-ballistic missile (ABM) system developed by the US Army during the late 1950s and early 1960s that was designed to destroy incoming Soviet intercontinental ballistic missile warheads before they could hit their targets. It was designed by Bell Labs' Nike team, and was initially based on the earlier Nike Hercules anti-aircraft missile. The original, Zeus A, was designed to intercept warheads in the upper atmosphere, mounting a 25 kiloton W31 nuclear warhead. During development, the concept changed to protect a much larger area and intercept the warheads at higher altitudes. This required the missile to be greatly enlarged into the totally new design, Zeus B, given the tri-service identifier XLIM-49, mounting a 400 kiloton W50 warhead. In several successful tests, the B model proved itself able to intercept warheads, and even satellites. The nature of the strategic threat changed dramatically during the period that Zeus was being developed. Originally expe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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