Stored Program Control
Stored program control (SPC) is a telecommunications technology for telephone exchanges. Its characteristic is that the switching system is controlled by a computer program stored in a memory in the switching system. SPC was the enabling technology of electronic switching systems (ESS) developed in the Bell System in the 1950s, and may be considered the third generation of switching technology. Stored program control was invented in 1954 by Bell Labs scientist Erna Schneider Hoover, who reasoned that computer software could control the connection of telephone calls. History Proposed and developed in the 1950s, SPC was introduced in production electronic switching systems in the 1960s. The 101ESS private branch exchange (PBX) was a transitional switching system in the Bell System to provide expanded services to business customers that were otherwise still served by an electromechanical central office switch. The first central office switch with SPC was installed at Morris, Illin ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Telephone Exchange
A telephone exchange, telephone switch, or central office is a central component of a telecommunications system in the public switched telephone network (PSTN) or in large enterprises. It facilitates the establishment of communication circuits, enabling telephone calls between subscribers. The term "central office" can also refer to a central location for fiber optic equipment for a fiber internet provider. In historical perspective, telecommunication terminology has evolved with time. The term ''telephone exchange'' is often used synonymously with ''central office'', a Bell System term. A central office is defined as the telephone switch controlling connections for one or more central office prefixes. However, it also often denotes the building used to house the inside plant equipment for multiple telephone exchange areas. In North America, the term ''wire center'' may be used to denote a central office location, indicating a facility that provides a telephone with a dial tone ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Flying-spot Store
The flying-spot store was an optical digital memory used in early stored program control components of electronic switching systems. The flying-spot store used a photographic plate as the store of binary data. Each ''spot'' on the plate was an opaque (logical 0) or transparent (logical 1) area that stored one bit. Spots were read and written with an optical mechanism with an access time of ca. one microsecond. The optical system consisted of a cathode ray tube that functioned as a flying-spot scanner, the source of light beams produced on its face and focused onto the photographic plates with a system of lenses. A photomultiplier detected the light beam. The light beam could be split into several components to read multiple plates simultaneously, permitting the formation of a group of bits for each location. A flying-spot store was the main permanent program and data memory for the first electronic central office installed on a trial basis in Morris, Illinois in 1960. The memory w ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Morris, Illinois
Morris is a city in and the county seat of Grundy County, Illinois, Grundy County, Illinois, United States and part of the southwest Chicago metropolitan area. The population was 14,163 as of the 2020 United States census, 2020 census. A team of ten anthropologists and sociologists from nearby University of Chicago studied the city in depth and reported its findings in W. Lloyd Warner, editor, ''Democracy in Jonesville: A Study of Quality and Inequality'' (1949). Description Morris is the Grundy County seat and has a large hospital and modern schools. It is home to the Morris Community High School Redskins, who have won three state championships in football. There are many small parks, ball diamonds, tennis courts, two golf courses, an outdoor swimming pool, an indoor short course pool as well as the Gebhard Woods State Park and the William G. Stratton State Park for boat launching on the Illinois River and a skatepark located near White Oak elementary school. Morris Community ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Fault-tolerant Design
Fault tolerance is the ability of a system to maintain proper operation despite failures or faults in one or more of its components. This capability is essential for high-availability, mission-critical, or even life-critical systems. Fault tolerance specifically refers to a system's capability to handle faults without any degradation or downtime. In the event of an error, end-users remain unaware of any issues. Conversely, a system that experiences errors with some interruption in service or graceful degradation of performance is termed 'resilient'. In resilience, the system adapts to the error, maintaining service but acknowledging a certain impact on performance. Typically, fault tolerance describes computer systems, ensuring the overall system remains functional despite hardware or software issues. Non-computing examples include structures that retain their integrity despite damage from fatigue, corrosion or impact. History The first known fault-tolerant computer was S ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Computer Memory
Computer memory stores information, such as data and programs, for immediate use in the computer. The term ''memory'' is often synonymous with the terms ''RAM,'' ''main memory,'' or ''primary storage.'' Archaic synonyms for main memory include ''core'' (for magnetic core memory) and ''store''. Main memory operates at a high speed compared to mass storage which is slower but less expensive per bit and higher in capacity. Besides storing opened programs and data being actively processed, computer memory serves as a Page cache, mass storage cache and write buffer to improve both reading and writing performance. Operating systems borrow RAM capacity for caching so long as it is 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 computer memory is implemented as semiconductor memory, where data is stored within memory cell (com ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Stored-program Computer
A stored-program computer is a computer that stores program instructions in electronically, electromagnetically, or optically accessible memory. This contrasts with systems that stored the program instructions with plugboards or similar mechanisms. The definition is often extended with the requirement that the treatment of programs and data in memory be interchangeable or uniform. Description In principle, stored-program computers have been designed with various architectural characteristics. A computer with a von Neumann architecture stores program data and instruction data in the same memory, while a computer with a Harvard architecture has separate memories for storing program and data. However, the term ''stored-program computer'' is sometimes used as a synonym for the von Neumann architecture. Jack Copeland considers that it is "historically inappropriate, to refer to electronic stored-program digital computers as 'von Neumann machines. Hennessy and Patterson wrote th ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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VoIP
Voice over Internet Protocol (VoIP), also known as IP telephony, is a set of technologies used primarily for voice communication sessions over Internet Protocol (IP) networks, such as the Internet. VoIP enables voice calls to be transmitted as data packets, facilitating various methods of voice communication, including traditional applications like Skype, Microsoft Teams, Google Voice, and VoIP phones. Regular telephones can also be used for VoIP by connecting them to the Internet via analog telephone adapters (ATAs), which convert traditional telephone signals into digital data packets that can be transmitted over IP networks. The broader terms Internet telephony, broadband telephony, and broadband phone service specifically refer to the delivery of voice and other communication services, such as fax, SMS, and voice messaging, over the Internet, in contrast to the traditional public switched telephone network (PSTN), commonly known as plain old telephone service (POTS) ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Softswitch
A softswitch (''software switch'') is a call-switching node in a telecommunications network, based not on the specialized switching hardware of the traditional telephone exchange, but implemented in software running on a general-purpose computing platform. Like its traditional counterparts it connects telephone calls between subscribers or other switching systems across a telecommunication network. Often a softswitch is implemented to switch calls using voice over IP (VoIP) technologies, but hybrid systems exist. Although the term ''softswitch'' technically refers to any such device, it is conventionally applied to a device that handles IP-to- IP phone calls, while the phrase '' access server'' or "media gateway" is used to refer to devices that either originate or terminate traditional land line phone calls. In practice, such devices can often do both. An access server might take a mobile call or a call originating from a traditional telephone line, convert it to IP traffic, the ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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CODEC
A codec is a computer hardware or software component that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or data stream, and hence is a type of codec. ''Endec'' is a portmanteau of encoder/decoder. A coder or encoder encodes a data stream or a signal for transmission or storage, possibly in encrypted form, and the decoder function reverses the encoding for playback or editing. Codecs are used in videoconferencing, streaming media, and video editing applications. History Originally, in the mid-20th century, a codec was a hardware device that coded analog signals into digital form using pulse-code modulation (PCM). Later, the term was also applied to software for converting between digital signal formats, including companding functions. Examples An audio codec converts analog audio signals into digital signals for transmissi ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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System X (telephony)
System X is the digital switching system installed in almost all telephone exchanges throughout the United Kingdom, from 1980 onwards. History Development System X was developed by Post Office Telecommunications (later to become British Telecom), GEC, Plessey, and Standard Telephones and Cables (STC), and was first shown in public in 1979 at the Telecom 79 exhibition in Geneva, Switzerland. STC withdrew from the project in 1982. In 1988, the telecommunications divisions of GEC and Plessey merged to form GPT, with Plessey subsequently being bought out by GEC and Siemens. In the late 1990s, GEC acquired Siemens' 40% stake in GPT. GEC renamed itself Marconi in 1999. When Marconi was sold to Ericsson in January 2006, Telent plc retained System X and continues to support and develop it as part of its UK services business. Implementation The first System X unit to enter public service, in September 1980, was installed in Baynard House, London and was a 'tandem junction unit ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Alcatel (mobile Device Brand)
Alcatel is a French brand of mobile handsets owned by Finnish telecommunications company Nokia and used under license by Chinese electronics company TCL Technology. The brand originates with former French conglomerate Alcatel, who began building mobile phones since at least 1991. At the time known as Alcatel One Touch, the brand was licensed in 2005 to TCL, who have ever since held sole rights from Alcatel's successors, Alcatel-Lucent and Nokia, having produced various handsets as well as other handheld devices mostly in the budget sector. Brand and company history Alcatel/CGE introduced its first cellular phone in the 1980s under France's analog network. As of 1996, Alcatel sold approximately one million mobile phone handsets. Handsets were manufactured in France at factories in Illkirch and Laval. In the year 1998, Alcatel became the 5th largest global mobile phone maker with a share of 4.3%, shipping between 7 and 8 million handsets. In 1999 it sold 11.5 million for a 4.1 ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |