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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] |
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] |
Electronic Switching System
In telecommunications, an electronic switching system (ESS) is a telephone switch that uses solid-state electronics, such as digital electronics and computerized common control, to interconnect telephone circuits for the purpose of establishing telephone calls. The generations of telephone switches before the advent of electronic switching in the 1950s used purely electro-mechanical relay systems and analog voice paths. These early machines typically utilized the step-by-step technique. The first generation of electronic switching systems in the 1960s were not entirely digital in nature, but used reed relay-operated metallic paths or crossbar switches operated by stored program control (SPC) systems. First announced in 1955, the first customer trial installation of an all-electronic central office commenced in Morris, Illinois in November 1960 by Bell Laboratories. The first large-scale electronic switching system was the Number One Electronic Switching System (1ESS) of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photographic Plate
Photographic plates preceded film as the primary medium for capturing images in photography. These plates, made of metal or glass and coated with a light-sensitive emulsion, were integral to early photographic processes such as heliography, daguerreotypes, and photogravure. Glass plates, thinner than standard window glass, became widely used in the late 19th century for their clarity and reliability. Although largely replaced by film during the 20th century, plates continued to be used for specialised scientific and medical purposes until the late 20th century. History Glass plates were far superior to film for research-quality imaging because they were stable and less likely to bend or distort, especially in large-format frames for wide-field imaging. Early plates used the wet collodion process. The wet plate process was replaced late in the 19th century by gelatin dry plates. A view camera nicknamed "The Mammoth" weighing was built by George R. Lawrence in 1899, sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathode Ray Tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms on an oscilloscope, a Film frame, frame of video on an Analog television, analog television set (TV), Digital imaging, digital raster graphics on a computer monitor, or other phenomena like radar targets. A CRT in a TV is commonly called a picture tube. CRTs have also been Williams tube, used as memory devices, in which case the screen is not intended to be visible to an observer. The term ''cathode ray'' was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons. In CRT TVs and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster scan, raster. In color devices, an image is produced by con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flying-spot Scanner
A flying-spot scanner (FSS) uses a scanning source of a spot of light, such as a high-resolution, high-light-output, low-persistence cathode ray tube (CRT), to scan an image. Usually the image to be scanned is on photographic film, such as motion picture film, or a slide or photographic plate. The output of the scanner is usually a television signal. Basic principle In the case of the CRT-based scanner, as an electron beam is drawn across the face of the CRT it creates a scan that has the correct number of lines and aspect ratio for the format of the signal. The image of this scan is focused with a lens onto the film frame. Its light passes through the image being scanned and is converted to a proportional electrical signal by photomultiplier tube(s), one for each color (red, green, blue), that detects the variations in intensity of the beam spot as it scans across the film, and are converted to proportional electrical signals, one for each of the color channels. Telecines that u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photomultiplier
A photomultiplier is a device that converts incident photons into an electrical signal. Kinds of photomultiplier include: * Photomultiplier tube, a vacuum tube converting incident photons into an electric signal. Photomultiplier tubes (PMTs for short) are members of the class of vacuum tubes, and more specifically vacuum phototubes, which are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum. ** Magnetic photomultiplier, developed by the Soviets in the 1930s. ** Electrostatic photomultiplier, a kind of photomultiplier tube demonstrated by Jan Rajchman of RCA Laboratories in Princeton, NJ in the late 1930s which became the standard for all future commercial photomultipliers. The first mass-produced photomultiplier, the Type 931, was of this design and is still commercially produced today. * Silicon photomultiplier, a solid-state device converting incident photons into an electric signal. Silicon photomul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell Laboratories Record
''Bell Laboratories Record'' (BLR) was a publication of the ''Bureau of Publication'' of the American Telephone and Telegraph Company (AT&T) and Bell Laboratories. It commenced distribution as a house organ for the employees and associates of the laboratories and the Bell System in September 1925, shortly after the founding of Bell Labs as a separate corporate entity. The first ''Director of Publication'' was John Mills, leading three managing and assisting editors, and an eleven-member editorial advisory board. The magazine reported personal, scientific, and organizational information, scholarly articles, and news of interest within the laboratories, Western Electric, and AT&T. It included descriptions of technologies created at many Bell System locations for basic research, devices, technologies, systems, and operations research relevant to telephone company, manufacturing, and government applications. It was slimmer and less scholarly than the ''Bell Labs Technical Journal''. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Storage Tube
Storage tubes are a class of cathode-ray tubes (CRTs) that are designed to hold an image for a long period of time, typically as long as power is supplied to the tube. A specialized type of storage tube, the Williams tube, was used as a main memory system on a number of early computers, from the late 1940s into the early 1950s. They were replaced with other technologies, notably core memory, starting in the 1950s. In a new form, the bistable tube, storage tubes made a comeback in the 1960s and 1970s for use in computer graphics, most notably the Tektronix 4010 series. Today they are obsolete, their functions provided by low-cost memory devices and liquid crystal displays. Operation Background A conventional CRT consists of an electron gun at the back of the tube that is aimed at a thin layer of phosphor at the front of the tube. Depending on the role, the beam of electrons emitted by the gun is steered around the display using magnetic (television) or electrostatic (oscillo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1ESS Switch
The Number One Electronic Switching System (1ESS) was the first large-scale stored program control (SPC) telephone exchange or electronic switching system in the Bell System. It was manufactured by Western Electric and first placed into service in Succasunna, New Jersey, in May 1965. The switching fabric was composed of a reed relay matrix controlled by wire spring relays which in turn were controlled by a central processing unit (CPU). The 1AESS central office switch was a plug compatible, higher capacity upgrade from 1ESS with a faster 1A processor that incorporated the existing instruction set for programming compatibility, and used smaller remreed switches, fewer relays, and featured disk storage. It was in service from 1976 to 2017. Switching fabric The voice switching fabric plan was similar to that of the earlier 5XB switch in being bidirectional and in using the call-back principle. The largest full-access matrix switches (the 12A line grids had partial acces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
