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Sinclair Wrist Calculator
The Sinclair Wrist Calculator was a wrist-worn calculator produced by Sinclair Instrument and introduced in 1977. History The Wrist Calculator was launched in February 1977 by Sinclair Instrument, a company established in parallel to Sinclair Radionics when the latter started to encounter financial difficulties. It was only available as a mail-order kit, and cost around . Despite the difficulty in assembling the kit due to the small size of the parts and their variability in specification, 10,000 were sold around the world. 20,000 were exported to the United States, but most went unsold and were returned to Sinclair. It was described as an "utter dud" and "impossible-to-build" by the journal ''International Design''. Design The design used 10 keys, with a three-position switch to select the correct function. The switch was held to the left to access the functions to the left above the keys, and to the right to get the functions to the right above the keys. In the centre position ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinclair Instrument
Sinclair Research Ltd is a British consumer electronics company founded by Clive Sinclair in Cambridge. It was originally incorporated in 1973 as Westminster Mail Order Ltd, renamed Sinclair Instrument Ltd, then Science of Cambridge Ltd, then Sinclair Computers Ltd, and finally Sinclair Research Ltd. It remained dormant until 1976, when it was activated with the intention of continuing Sinclair's commercial work from his earlier company Sinclair Radionics, and adopted the name Sinclair Research in 1981. In 1980, Clive Sinclair entered the home computer market with the ZX80 at £99.95, at that time the cheapest personal computer for sale in the United Kingdom. In 1982 the ZX Spectrum was released, becoming the UK's best selling computer, and competing aggressively against Commodore and Amstrad. At the height of its success, and largely inspired by the Japanese Fifth Generation Computer program, the company established the "MetaLab" research centre at Milton Hall near Cambridg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mostek
Mostek was a semiconductor integrated circuit manufacturer, founded in 1969 by L. J. Sevin, Louay E. Sharif, Richard L. Petritz and other ex-employees of Texas Instruments. At its peak in the late 1970s, Mostek held an 85% market share of the dynamic random-access memory (DRAM) memory chip market worldwide, until being eclipsed by lower-priced Japanese DRAM manufacturers who were accused of dumping memory on the market. Initially Mostek products were manufactured in Worcester, Massachusetts in cooperation with Sprague Electric, however by 1974 most of its manufacturing was done in the Carrollton, Texas facility on Crosby Road. In 1979, soon after its market peak, Mostek was purchased by United Technologies Corporation for . In 1985, after several years of red ink and declining market share, UTC closed Mostek completely and sold it for to the French electronics firm Thomson-CSF, which later spun it off into STMicroelectronics. Early Products Mostek's first contract was from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light-emitting Diode
A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device. Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared (IR) light. Infrared LEDs are used in remote-control circuits, such as those used with a wide variety of consumer electronics. The first visible-light LEDs were of low intensity and limited to red. Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. Later developments produced LEDs available in visible, ultraviolet (UV) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinclair Radionics
Sinclair Radionics Ltd was a company founded by Sir Clive Sinclair in Cambridge, England which developed hi-fi products, radios, calculators and scientific instruments. History After raising funds to start the business by writing articles for ''Practical Wireless'' magazine, and borrowing £50, Clive Sinclair founded Sinclair Radionics Ltd. on 25 July 1961. Sinclair initially worked alone in the evenings in a room in London (he was still a technical journalist during the day), selling radio kits by mail order. Radios and Hi-Fi Radionics initially developed hi-fi equipment; it released its first product, the Sinclair Micro-amplifier, in December 1962. The assembly and distribution of this product were contracted out to Cambridge Consultants. In 1963 Sinclair Radionics introduced their first radio with the "Sinclair Slimline" in kit form at forty-nine shillings and sixpence (£2.47½). A year later, in 1964, Sinclair released the "X-10" amplifier, one of the first comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Switch
In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of switch is an electromechanical device consisting of one or more sets of movable electrical contacts connected to external circuits. When a pair of contacts is touching current can pass between them, while when the contacts are separated no current can flow. Switches are made in many different configurations; they may have multiple sets of contacts controlled by the same knob or actuator, and the contacts may operate simultaneously, sequentially, or alternately. A switch may be operated manually, for example, a light switch or a keyboard button, or may function as a sensing element to sense the position of a machine part, liquid level, pressure, or temperature, such as a thermostat. Many specialized forms exist, such as the toggle switch, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algebraic Logic
In mathematical logic, algebraic logic is the reasoning obtained by manipulating equations with free variables. What is now usually called classical algebraic logic focuses on the identification and algebraic description of models appropriate for the study of various logics (in the form of classes of algebras that constitute the algebraic semantics for these deductive systems) and connected problems like representation and duality. Well known results like the representation theorem for Boolean algebras and Stone duality fall under the umbrella of classical algebraic logic . Works in the more recent abstract algebraic logic (AAL) focus on the process of algebraization itself, like classifying various forms of algebraizability using the Leibniz operator . Calculus of relations A homogeneous binary relation is found in the power set of ''X'' × ''X'' for some set ''X'', while a heterogeneous relation is found in the power set of ''X'' × ''Y'', where ''X'' ≠ ''Y''. Whether a g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse Polish Notation
Reverse Polish notation (RPN), also known as reverse Łukasiewicz notation, Polish postfix notation or simply postfix notation, is a mathematical notation in which operators ''follow'' their operands, in contrast to Polish notation (PN), in which operators ''precede'' their operands. It does not need any parentheses as long as each operator has a fixed number of operands. The description "Polish" refers to the nationality of logician Jan Łukasiewicz, who invented Polish notation in 1924. The first computer to use postfix notation, though it long remained essentially unknown outside of Germany, was Konrad Zuse's Z3 in 1941 as well as his Z4 in 1945. The reverse Polish scheme was again proposed in 1954 by Arthur Burks, Don Warren, and Jesse Wright and was independently reinvented by Friedrich L. Bauer and Edsger W. Dijkstra in the early 1960s to reduce computer memory access and use the stack to evaluate expressions. The algorithms and notation for this scheme were extended ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
