Subroutines
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Subroutines
In computer programming, a function (also procedure, method, subroutine, routine, or subprogram) is a callable unit of software logic that has a well-defined interface and behavior and can be invoked multiple times. Callable units provide a powerful programming tool. The primary purpose is to allow for the decomposition of a large and/or complicated problem into chunks that have relatively low cognitive load and to assign the chunks meaningful names (unless they are anonymous). Judicious application can reduce the cost of developing and maintaining software, while increasing its quality and reliability. Callable units are present at multiple levels of abstraction in the programming environment. For example, a programmer may write a function in source code that is compiled to machine code that implements similar semantics. There is a callable unit in the source code and an associated one in the machine code, but they are different kinds of callable units with different implic ...
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Call Stack
In computer science, a call stack is a Stack (abstract data type), stack data structure that stores information about the active subroutines and block (programming), inline blocks of a computer program. This type of stack is also known as an execution stack, program stack, control stack, run-time stack, or machine stack, and is often shortened to simply the "stack". Although maintenance of the call stack is important for the proper functioning of most software, the details are normally hidden and automatic in high-level programming languages. Many computer instruction sets provide special instructions for manipulating stacks. A call stack is used for several related purposes, but the main reason for having one is to keep track of the point to which each active subroutine should return control when it finishes executing. An active subroutine is one that has been called, but is yet to complete execution, after which control should be handed back to the point of call. Such activatio ...
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Computer Programming
Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing source code, code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the Domain (software engineering), application domain, details of programming languages and generic code library (computing), libraries, specialized algorithms, and Logic#Formal logic, formal logic. Auxiliary tasks accompanying and related to programming include Requirements analysis, analyzing requirements, Software testing, testing, debugging (investigating and fixing problems), imple ...
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C Sharp (programming Language)
C# ( pronounced: C-sharp) ( ) is a general-purpose high-level programming language supporting multiple paradigms. C# encompasses static typing, strong typing, lexically scoped, imperative, declarative, functional, generic, object-oriented (class-based), and component-oriented programming disciplines. The principal inventors of the C# programming language were Anders Hejlsberg, Scott Wiltamuth, and Peter Golde from Microsoft. It was first widely distributed in July 2000 and was later approved as an international standard by Ecma (ECMA-334) in 2002 and ISO/ IEC (ISO/IEC 23270 and 20619) in 2003. Microsoft introduced C# along with .NET Framework and Microsoft Visual Studio, both of which are technically speaking, closed-source. At the time, Microsoft had no open-source products. Four years later, in 2004, a free and open-source project called Microsoft Mono began, providing a cross-platform compiler and runtime environment for the C# programming language. A decad ...
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Automatic Computing Engine
The Automatic Computing Engine (ACE) was a British early Electronic storage, electronic Serial computer, serial stored-program computer design by Alan Turing. Turing completed the ambitious design in late 1945, having had experience in the years prior with the secret Colossus computer, Colossus computer at Bletchley Park. The ACE was not built, but a smaller version, the Pilot ACE, was constructed at the National Physical Laboratory (United Kingdom), National Physical Laboratory and became operational in 1950. A larger implementation of the ACE design was the MOSAIC computer which became operational in 1955. ACE also led to the Bendix G-15 and other computers. Background The project was managed by John R. Womersley, superintendent of the Mathematics Division of the National Physical Laboratory, UK, National Physical Laboratory (NPL). The use of the word ''Engine'' was in homage to Charles Babbage and his Difference Engine and Analytical Engine. Turing's technical design ''Pro ...
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Alan Turing
Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher and theoretical biologist. He was highly influential in the development of theoretical computer science, providing a formalisation of the concepts of algorithm and computation with the Turing machine, which can be considered a model of a general-purpose computer. Turing is widely considered to be the father of theoretical computer science. Born in London, Turing was raised in southern England. He graduated from University of Cambridge, King's College, Cambridge, and in 1938, earned a doctorate degree from Princeton University. During World War II, Turing worked for the Government Code and Cypher School at Bletchley Park, Britain's codebreaking centre that produced Ultra (cryptography), Ultra intelligence. He led Hut 8, the section responsible for German naval cryptanalysis. Turing devised techniques for speeding the breaking of Germ ...
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Macro (computer Science)
In computer programming, a macro (short for "macro instruction"; ) is a rule or pattern that specifies how a certain input should be mapped to a replacement output. Applying a macro to an input is known as macro expansion. The input and output may be a sequence of lexical tokens or characters, or a syntax tree. Character macros are supported in software applications to make it easy to invoke common command sequences. Token and tree macros are supported in some programming languages to enable code reuse or to extend the language, sometimes for domain-specific languages. Macros are used to make a sequence of computing instructions available to the programmer as a single program statement, making the programming task less tedious and less error-prone. Thus, they are called "macros" because a "big" block of code can be expanded from a "small" sequence of characters. Macros often allow positional or keyword parameters that dictate what the conditional assembler program gen ...
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Stanley Gill
Professor Stanley Gill (26 March 1926 – 5 April 1975) was a British computer scientist credited, along with Maurice Wilkes and David Wheeler, with the invention of the first computer subroutine. Early life, education and career Stanley Gill was born 26 March 1926 in Worthing, West Sussex, England. He was educated at Worthing High School for Boys and was, during his schooldays, a member of an amateur dramatic society. In 1943, he was awarded a State Scholarship and went to St John's College, Cambridge, where he read Mathematics/Natural Sciences. He graduated BA in 1947 and MA in 1950. Gill worked at the National Physical Laboratory from 1947 to 1950, where he met his wife, Audrey Lee, whom he married in 1949. From 1952 to 1955 he was a Research Fellow at St John's working in a team led by Maurice Wilkes; the research involved pioneering work with the EDSAC computer in the Cavendish Laboratory. In 1952, he developed a very early computer game. It involved a dot (termed a sh ...
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David Wheeler (British Computer Scientist)
David John Wheeler (9 February 1927 – 13 December 2004) was an English computer scientist and professor of computer science at the University of Cambridge. Education Wheeler was born in Birmingham, England, the second of the three children of (Agnes) Marjorie, ''née'' Gudgeon, and Arthur Wheeler, a press tool maker, engineer, and proprietor of a small shopfitting firm. He was educated at a local primary school in Birmingham and then went on to King Edward VI Camp Hill School after winning a scholarship in 1938. His education was disrupted by World War II, and he completed his sixth form studies at Hanley High School. In 1945 he gained a scholarship to study the Cambridge Mathematical Tripos at Trinity College, Cambridge, graduating in 1948. He was awarded the world's first PhD in computer science in 1951. Career Wheeler's contributions to the field included work on the Electronic Delay Storage Automatic Calculator (EDSAC) in the 1950s and the Burrows–Wheeler t ...
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Maurice Wilkes
Sir Maurice Vincent Wilkes (26 June 1913 – 29 November 2010) was an English computer scientist who designed and helped build the EDSAC, Electronic Delay Storage Automatic Calculator (EDSAC), one of the earliest stored-program computers, and who invented microprogramming, a method for using stored-program logic to operate the control unit of a central processing unit's circuits. At the time of his death, Wilkes was an Emeritus, Emeritus Professor at the University of Cambridge. Early life, education, and military service Wilkes was born in Dudley, Worcestershire, England the only child of Ellen (Helen), née Malone (1885–1968) and Vincent Joseph Wilkes (1887–1971), an accounts clerk at the estate of the Earl of Dudley. He grew up in Stourbridge, West Midlands, and was educated at King Edward VI College, Stourbridge. During his school years he was introduced to amateur radio by his chemistry teacher. He studied the Mathematical Tripos at St John's College, Cambr ...
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EDVAC
EDVAC (Electronic Discrete Variable Automatic Computer) was one of the earliest electronic computers. It was built by Moore School of Electrical Engineering at the University of Pennsylvania. Along with ORDVAC, it was a successor to the ENIAC. Unlike ENIAC, it was binary rather than decimal, and was designed to be a stored-program computer. ENIAC inventors, John Mauchly and J. Presper Eckert, proposed the EDVAC's construction in August 1945. A contract to build the new computer was signed in April 1946 with an initial budget of US$100,000. EDVAC was delivered to the Ballistic Research Laboratory in 1949. The Ballistic Research Laboratory became a part of the US Army Research Laboratory in 1952. Functionally, EDVAC was a binary serial computer with automatic addition, subtraction, multiplication, programmed division and automatic checking with an ultrasonic serial memory having a capacity of 1,024 44-bit words. EDVAC's average addition time was 864 microseconds and it ...
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ENIAC
ENIAC (; Electronic Numerical Integrator and Computer) was the first Computer programming, programmable, Electronics, electronic, general-purpose digital computer, completed in 1945. Other computers had some of these features, but ENIAC was the first to have them all. It was Turing-complete and able to solve "a large class of numerical problems" through reprogramming. ENIAC was designed by John Mauchly and J. Presper Eckert to calculate artillery external ballistics, firing tables for the United States Army's Ballistic Research Laboratory (which later became a part of the United States Army Research Laboratory, Army Research Laboratory). However, its first program was a study of the feasibility of the thermonuclear weapon. ENIAC was completed in 1945 and first put to work for practical purposes on December 10, 1945.* ENIAC was formally dedicated at the University of Pennsylvania on February 15, 1946, having cost $487,000 (), and called a "Giant Brain" by the press. It had ...
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Kathleen Antonelli
Kathleen Rita Antonelli ( McNulty; formerly Mauchly; 12 February 1921 – 20 April 2006), known as Kay McNulty, was an Irish computer programmer and one of the six original programmers of the ENIAC, one of the first general-purpose electronic digital computers. The other five ENIAC programmers were Betty Holberton, Ruth Teitelbaum, Frances Spence, Marlyn Meltzer, and Jean Bartik. Early life and education She was born Kathleen Rita McNulty in Feymore, part of the small village of Creeslough in what was then a ''Gaeltacht'' area (Irish-speaking region) of County Donegal in Ulster, the northern province in Ireland, on February 12, 1921, during the Irish War of Independence. She was the third of six children of James and Anne (née Nelis) McNulty. On the night of her birth, her father, an Irish Republican Army training officer, was arrested and imprisoned in Derry Gaol for two years as he was a suspected member of the IRA. On his release, the family emigrated to the Un ...
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