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Partial-response Maximum-likelihood
In computer data storage, partial-response maximum-likelihood (PRML) is a method for recovering the digital data from the weak analog read-back signal picked up by the head of a magnetic disk drive or tape drive. PRML was introduced to recover data more reliably or at a greater areal-density than earlier simpler schemes such as peak-detection. These advances are important because most of the digital data in the world is stored using magnetic storage on hard disk or tape drives. Ampex introduced PRML in a tape drive in 1984. IBM introduced PRML in a disk drive in 1990 and also coined the acronym PRML. Many advances have taken place since the initial introduction. Recent read/write channels operate at much higher data-rates, are fully adaptive, and, in particular, include the ability to handle nonlinear signal distortion and non-stationary, colored, data-dependent noise ( PDNP or NPML). ''Partial response'' refers to the fact that part of the response to an individual bit may occ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Data Storage
Computer data storage or digital data storage is a technology consisting of computer components and Data storage, recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer is what manipulates data by performing computations. In practice, almost all computers use a storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but less expensive and larger options further away. Generally, the fast technologies are referred to as "memory", while slower persistent technologies are referred to as "storage". Even the first computer designs, Charles Babbage's Analytical Engine and Percy Ludgate's Analytical Machine, clearly distinguished between processing and memory (Babbage stored numbers as rotations of gears, while Ludgate stored numbers as displacements of rods in shuttles). This distinction was extended in the Von Neumann archite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dave Forney
George David Forney Jr. (born March 6, 1940) is an American electrical engineer who made contributions in telecommunication system theory, specifically in coding theory and information theory. Biography Forney received the B.S.E. degree in electrical engineering from Princeton University in 1961, summa cum laude, and the M.S. and Sc.D. degrees in electrical engineering from the Massachusetts Institute of Technology in 1963 and 1965, respectively. His Sc.D thesis introduced the idea of concatenated codes. He is a member of the United States National Academy of Engineering (1989) and National Academy of Sciences (2003). He is a long-time faculty member at the Massachusetts Institute of Technology. Among other things, he is generally credited with being the first to recognize the optimality and practical importance of the Viterbi algorithm, and his tutorial paper on the subject is widely cited. His work in the Viterbi algorithm and in advancing the understanding of coding theory i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plastic Leaded Chip Carrier
In electronics, a chip carrier is one of several kinds of surface-mount technology packages for integrated circuits (commonly called "chips"). Connections are made on all four edges of a square package; compared to the internal cavity for mounting the integrated circuit, the package overall size is large.Kenneth Jackson, Wolfgang Schroter, (ed), ''Handbook of Semiconductor Technology Volume 2'', Wiley VCH, 2000, , page 627 Types Chip carriers may have either J-shaped metal leads for connections by solder or by a socket, or may be lead-less with metal pads for connections. If the leads extend beyond the package, the preferred description is " flat pack". Chip carriers can be smaller than dual in-line packages and since they use all four edges of the package they can have a larger pin count. Chip carriers may be made of ceramic or plastic. Some forms of chip carrier package are standardized in dimensions and registered with trade industry associations such as JEDEC. Other forms a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Switzerland
Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland is geographically divided among the Swiss Plateau, the Swiss Alps, Alps and the Jura Mountains, Jura; the Alps occupy the greater part of the territory, whereas most of the country's Demographics of Switzerland, 9 million people are concentrated on the plateau, which hosts List of cities in Switzerland, its largest cities and economic centres, including Zurich, Geneva, and Lausanne. Switzerland is a federal republic composed of Cantons of Switzerland, 26 cantons, with federal authorities based in Bern. It has four main linguistic and cultural regions: German, French, Italian and Romansh language, Romansh. Although most Swiss are German-speaking, national identity is fairly cohesive, being rooted in a common historical background, shared ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Zurich
IBM Research is the research and development division for IBM, an American multinational information technology company. IBM Research is headquartered at the Thomas J. Watson Research Center in Yorktown Heights, New York, near IBM headquarters in Armonk, New York. It is the largest industrial research organization in the world with operations in over 170 countries and twelve labs on six continents. IBM employees have garnered six Nobel Prizes, six Turing Awards, 20 inductees into the U.S. National Inventors Hall of Fame, 19 National Medals of Technology, five National Medals of Science and three Kavli Prizes. , the company has generated more patents than any other business in each of 25 consecutive years, which is a record. History The roots of today's IBM Research began with the 1945 opening of the Watson Scientific Computing Laboratory at Columbia University. This was the first IBM laboratory devoted to pure science and later expanded into additional IBM Research locations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Rochester
The Rochester Technology Campus is a facility shared by several companies in Rochester, Minnesota. The initial structure was designed by Eero Saarinen, who clad the structure in blue panels of varying hues after being inspired by the Minnesota sky and the nickname of the first occupant, Big Blue. History Early years IBM's CEO Thomas J. Watson Jr. reportedly chose the site of Rochester in honor of his copilot during World War II, Leland Fiegel, who lived there. Groundbreaking took place on July 31, 1956. When it was first completed, there was of floor space. After expansion, it has on the main campus, more than half the size of the Pentagon in Arlington, Virginia. The building was first dedicated in 1958, but has been expanded considerably since then. Current developments Employment at the site has gone through several cycles of growth and collapse, but is over twice what it was in the 1950s. On May 4, 2016, it was announced that IBM would consolidate its remaining employ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of IBM Magnetic Disk Drives
IBM manufactured magnetic disk storage devices from 1956 to 2003, when it sold its hard disk drive business to Hitachi. Both the hard disk drive (HDD) and floppy disk drive (FDD) were invented by IBM and as such IBM's employees were responsible for many of the innovations in these products and their technologies. The basic mechanical arrangement of hard disk drives has not changed since the IBM 1301. Disk drive performance and characteristics are measured by the same standards now as they were in the 1950s. Few products in history have enjoyed such spectacular declines in cost and physical size along with equally dramatic improvements in capacity and performance. IBM manufactured 8-inch floppy disk drives from 1969 until the mid-1980s, but did not become a significant manufacturer of smaller-sized, 5.25- or 3.5-inch floppy disk drives (the dimension refers to the diameter of the floppy disk, not the size of the drive). IBM always offered its magnetic disk drives for sale but did no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analog-to-digital Converter
In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a Digital signal (signal processing), digital signal. An ADC may also provide an isolated measurement such as an electronic device that converts an analog input voltage or Electric current, current to a digital number representing the magnitude of the voltage or current. Typically the digital output is a two's complement binary number that is proportional to the input, but there are other possibilities. There are several ADC hardware architecture, architectures. Due to the complexity and the need for precisely matched electronic component, components, all but the most specialized ADCs are implemented as integrated circuits (ICs). These typically take the form of metal–oxide–semiconductor (MOS) mixed-signal integrated circuit chips that integrate both Analogue electronics, anal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plessey
The Plessey Company plc was a British electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after World War II by acquisition of companies and formed overseas companies. It was listed on the London Stock Exchange and was a constituent of the FTSE 100 Index. In 1989, it was taken over by a consortium formed by GEC and Siemens which split the assets of the Plessey group. The majority of Plessey's defence assets were amalgamated into BAE Systems in 1999 when British Aerospace merged with the defence arm of GEC, Marconi Electronic Systems (MES). The Plessey Microsystems division was the subject of a management buyout in 1988 becoming Radstone Technology, which survives today as part of Abaco Systems based in Towcester, Northamptonshire. The bulk of Plessey's telecommunications assets were acquired by Ericsson through its 2005 acquisition of Marconi Communications, a successor company of GEC. History E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Video Tape Recorder
A video tape recorder (VTR) is a tape recorder designed to record and playback video and audio signal, audio material from magnetic tape. The early VTRs were open-reel devices that record on individual reels of 2-inch-wide (5.08 cm) tape. They were used in television studios, serving as a replacement for motion picture film stock and making recording for television applications cheaper and quicker. Beginning in 1963, videotape machines made instant replay during televised sporting events possible. Improved formats, in which the tape was contained inside a videocassette, were introduced around 1969; the machines which play them are called videocassette recorders. An agreement by Japanese manufacturers on a common standard recording format, which allowed cassettes recorded on one manufacturer's machine to play on another's, made a consumer market possible; and the first consumer videocassette recorder, which used the U-matic format, was introduced by Sony in 1971. History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Coleman (engineer)
Charles Hubert Coleman Jr. (October 28, 1926 – July 13, 2005) was an American electronic engineer and a pioneer in the field of color video tape recording and later in high data-rate digital tape recording. He was also an amateur explorer and avid pilot. Early life Coleman was born on October 28, 1926, in Washington, DC and, as one of three children, grew up in Charleston, Illinois. His father was a professor of history at a state teacher's college. On his 17th birthday in October 1943, he joined the US Marines. Following boot camp, he was shipped to the Pacific and spent the remainder of the war teaching young Marines how to be radio technicians. Upon discharge in 1946, he joined WBKB-TV (now WBBM) in Chicago. In 1953, WBKB-TV was purchased by CBS Television. At CBS he quickly became a pioneer in the brand new field of video tape recording. Coleman invented Autotec time base correction and applied it to improve the quality of the black and white TV broadcasts from WBKB Car ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Run-length Limited
Run-length limited (RLL) is a line coding technique that is used to send arbitrary data over a communications channel with bandwidth limits. RLL codes are defined by four main parameters: ''m'', ''n'', ''d'', ''k''. The first two, ''m''/''n'', refer to the rate of the code, while the remaining two specify the minimal ''d'' and maximal ''k'' number of zeroes between consecutive ones. This is used in both telecommunication and storage systems that move a medium past a fixed recording head. Specifically, RLL bounds the length of stretches (runs) of repeated bits during which the signal does not change. If the runs are too long, clock recovery is difficult; if they are too short, the high frequencies might be attenuated by the communications channel. By modulating the data, RLL reduces the timing uncertainty in decoding the stored data, which would lead to the possible erroneous insertion or removal of bits when reading the data back. This mechanism ensures that the boundaries b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
