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Wheeler Jump
The Wheeler Jump is a type of subroutine call methodology that was used on some early computers that lacked hardware support for saving the return address. The concept was developed by David Wheeler while working on the pioneering EDSAC machine in the 1950s. EDSAC had not been built with subroutines in mind, and lacked a suitable processor register or a hardware stack that might allow the return address to be easily stored. Wheeler's solution was a particular way to write the subroutine code. To implement it, the last line of the subroutine was a "jump to this address" instruction, which would normally be followed by a memory location. In a Wheeler subroutine, this address was normally set to a dummy number, say 0. To call the routine, the address of the caller would be placed in the accumulator and then the code would jump to the starting point of the routine. The first instructions in the routine would calculate the return address based on the value in the accumulator, typica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subroutine Call
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 implica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David Wheeler (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 tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EDSAC
The Electronic Delay Storage Automatic Calculator (EDSAC) was an early British computer. Inspired by John von Neumann's seminal ''First Draft of a Report on the EDVAC'', the machine was constructed by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory in England to provide a service to the university. EDSAC was the second electronic digital stored-program computer, after the Manchester Mark 1, to go into regular service. Later the project was supported by J. Lyons and Co., J. Lyons & Co. Ltd., intending to develop a commercially applied computer and resulting in Lyons' development of the LEO (computer), LEO I, based on the EDSAC design. Work on EDSAC started during 1947, and it ran its first programs on 6 May 1949, when it calculated a table of square numbers and a list of prime numbers. EDSAC was finally shut down on 11 July 1958, having been superseded by EDSAC 2, which remained in use until 1965. Project and plan The concept ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Processor Register
A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-only. In computer architecture, registers are typically addressed by mechanisms other than main memory, but may in some cases be assigned a memory address e.g. DEC PDP-10, ICT 1900. Almost all computers, whether load/store architecture or not, load items of data from a larger memory into registers where they are used for arithmetic operations, bitwise operations, and other operations, and are manipulated or tested by machine instructions. Manipulated items are then often stored back to main memory, either by the same instruction or by a subsequent one. Modern processors use either static or dynamic random-access memory (RAM) as main memory, with the latter usually accessed via one or more cache levels. Processor registers are normal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hardware Stack
In computer science, a stack is an abstract data type that serves as a collection of elements with two main operations: * Push, which adds an element to the collection, and * Pop, which removes the most recently added element. Additionally, a peek operation can, without modifying the stack, return the value of the last element added. The name ''stack'' is an analogy to a set of physical items stacked one atop another, such as a stack of plates. The order in which an element added to or removed from a stack is described as last in, first out, referred to by the acronym LIFO. As with a stack of physical objects, this structure makes it easy to take an item off the top of the stack, but accessing a datum deeper in the stack may require removing multiple other items first. Considered a sequential collection, a stack has one end which is the only position at which the push and pop operations may occur, the ''top'' of the stack, and is fixed at the other end, the ''bottom''. A st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accumulator (computing)
In a computer's central processing unit (CPU), the accumulator is a register in which intermediate arithmetic logic unit results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to cache or main memory, perhaps only to be read right back again for use in the next operation. Accessing memory is slower than accessing a register like an accumulator because the technology used for the large main memory is slower (but cheaper) than that used for a register. Early electronic computer systems were often split into two groups, those with accumulators and those without. Modern computer systems often have multiple general-purpose registers that can operate as accumulators, and the term is no longer as common as it once was. However, to simplify their design, a number of special-purpose processors still use a single accumulator. Basic concept Mathematical operations often take ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recursion
Recursion occurs when the definition of a concept or process depends on a simpler or previous version of itself. Recursion is used in a variety of disciplines ranging from linguistics to logic. The most common application of recursion is in mathematics and computer science, where a function (mathematics), function being defined is applied within its own definition. While this apparently defines an infinite number of instances (function values), it is often done in such a way that no infinite loop or infinite chain of references can occur. A process that exhibits recursion is ''recursive''. Video feedback displays recursive images, as does an infinity mirror. Formal definitions In mathematics and computer science, a class of objects or methods exhibits recursive behavior when it can be defined by two properties: * A simple ''base case'' (or cases) — a terminating scenario that does not use recursion to produce an answer * A ''recursive step'' — a set of rules that reduce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EDSAC 2
EDSAC 2 was an early vacuum tube computer (operational in 1958), the successor to the Electronic Delay Storage Automatic Calculator (EDSAC). It was the first computer to have a microprogrammed control unit and a bit-slice hardware architecture. First calculations were performed on the incomplete machine in 1957. Calculations about elliptic curves performed on EDSAC-2 in the early 1960s led to the Birch and Swinnerton-Dyer conjecture, a Millennium Prize Problem, unsolved as of 2024. And in 1963, Frederick Vine and Drummond Matthews used EDSAC 2 to generate a magnetic anomaly map of the seafloor from data collected in the Indian Ocean by H.M.S. Owen, key evidence that helped support the theory of plate tectonics. EDSAC-2 was decommissioned in 1965, having been superseded by the Titan computer Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Assembler Language
In computing, assembly language (alternatively assembler language or symbolic machine code), often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. Assembly language usually has one statement per machine instruction (1:1), but constants, comments, assembler directives, symbolic labels of, e.g., memory locations, registers, and macros are generally also supported. The first assembly code in which a language is used to represent machine code instructions is found in Kathleen and Andrew Donald Booth's 1947 work, ''Coding for A.R.C.''. Assembly code is converted into executable machine code by a utility program referred to as an '' assembler''. The term "assembler" is generally attributed to Wilkes, Wheeler and Gill in their 1951 book ''The Preparation of Programs for an Electronic Digit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Computing In The United Kingdom
The United Kingdom has been involved with the Internet throughout its origins and development. The telecommunications infrastructure in the United Kingdom provides Internet access to homes and businesses mainly through fibre, cable, mobile and fixed wireless networks. The UK's 140-year-old copper network, maintained by Openreach, was set to be withdrawn by December 2025, although this has since been extended to 31st January 2027 in some areas due to reasons including panic alarms in sheltered housing needing a persistent connection which can't be guaranteed with internet-based DECT systems. The share of households with Internet access in the United Kingdom grew from 9 percent in 1998 to 93 percent in 2019. In 2019, virtually all adults aged 16 to 44 years in the UK were recent internet users (99%), compared with 47% of adults aged 75 years and over; in aggregate, the third-highest in Europe. Internet bandwidth per Internet user was the seventh highest in the world in 2016, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
