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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 integrate ... [...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 construc ... [...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] |
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