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🔗 Computing

Compound File Binary Format (CFBF), also called Compound File, Compound Document format, or Composite Document File V2 (CDF), is a compound document file format for storing numerous files and streams within a single file on a disk. CFBF is developed by Microsoft and is an implementation of Microsoft COM Structured Storage. The file format is used for storing storage objects and stream objects in a hierarchical structure within a single file.

Microsoft has opened the format for use by others and it is now used in a variety of programs from Microsoft Word and Microsoft Access to Business Objects. It also forms the basis of the Advanced Authoring Format.

🔗 Computing 🔗 Energy 🔗 Microsoft

The data furnace is a method of heating residential homes or offices by running computers in them, which release considerable amounts of waste heat. Data furnaces can theoretically be cheaper than storing computers in huge data centers because the higher cost of electricity in residential areas (when compared to industrial zones) can be offset by charging the home owner for the heat that the data center gives off. Some large companies that store and process thousands of gigabytes of data believe that data furnaces could be cheaper because there would be little to no overhead costs. The cost of a traditional data storage center is up to around $400 per server, whereas the overhead cost per server of a home data furnace is around $10. Individuals had already begun using computers as a heat source by 2011.

🔗 Computing

The Knights of the Lambda Calculus is a semi-fictional organization of expert Lisp and Scheme hackers. The name refers to the lambda calculus, a mathematical formalism invented by Alonzo Church, with which Lisp is intimately connected, and references the Knights Templar.

There is no actual organization that goes by the name Knights of the Lambda Calculus; it mostly only exists as a hacker culture in-joke. The concept most likely originated at MIT. For example, in the Structure and Interpretation of Computer Programs video lectures, Gerald Jay Sussman presents the audience with the button, saying they are now members of this special group. However, according to the Jargon File, a "well-known LISPer" has been known to give out buttons with Knights insignia on them, and some people have claimed to have membership in the Knights.

🔗 Computing

Seed7 is an extensible general-purpose programming language designed by Thomas Mertes. It is syntactically similar to Pascal and Ada. Along with many other features, it provides an extension mechanism. Seed7 supports introducing new syntax elements and their semantics into the language, and allows new language constructs to be defined and written in Seed7. For example, programmers can introduce syntax and semantics of new statements and user defined operator symbols. The implementation of Seed7 differs significantly from that of languages with hard-coded syntax and semantics.

🔗 Computing 🔗 Business 🔗 Computing/Software 🔗 Business/Accounting

VisiCalc (for "visible calculator") was the first spreadsheet computer program for personal computers, originally released for the Apple II by VisiCorp. It is often considered the application that turned the microcomputer from a hobby for computer enthusiasts into a serious business tool, prompting IBM to introduce the IBM PC two years later. VisiCalc is considered the Apple II's killer app. It sold over 700,000 copies in six years, and as many as 1 million copies over its history.

Initially developed for the Apple II using a 6502 assembler running on the Multics time sharing system, VisiCalc was ported to numerous platforms, both 8-bit and some of the early 16-bit systems. In order to do this, the company developed porting platforms that produced bug compatible versions. The company took the same approach when the IBM PC was launched, producing a product that was essentially identical to the original 8-bit Apple II version. Sales were initially brisk, with about 300,000 copies sold.

VisiCalc used the A1 notation in formulas.

When Lotus 1-2-3 was launched in 1983, taking full advantage of the expanded memory and screen of the PC, VisiCalc sales ended almost overnight. Sales declined so rapidly that the company was soon insolvent. Lotus Development purchased the company in 1985, and immediately ended sales of VisiCalc and the company's other products.

🔗 Computing

Constraint logic programming is a form of constraint programming, in which logic programming is extended to include concepts from constraint satisfaction. A constraint logic program is a logic program that contains constraints in the body of clauses. An example of a clause including a constraint is A(X,Y) :- X+Y>0, B(X), C(Y). In this clause, X+Y>0 is a constraint; A(X,Y), B(X), and C(Y) are literals as in regular logic programming. This clause states one condition under which the statement A(X,Y) holds: X+Y is greater than zero and both B(X) and C(Y) are true.

As in regular logic programming, programs are queried about the provability of a goal, which may contain constraints in addition to literals. A proof for a goal is composed of clauses whose bodies are satisfiable constraints and literals that can in turn be proved using other clauses. Execution is performed by an interpreter, which starts from the goal and recursively scans the clauses trying to prove the goal. Constraints encountered during this scan are placed in a set called constraint store. If this set is found out to be unsatisfiable, the interpreter backtracks, trying to use other clauses for proving the goal. In practice, satisfiability of the constraint store may be checked using an incomplete algorithm, which does not always detect inconsistency.

🔗 Computing 🔗 Computing/Computer Security

Christmas Tree EXEC was the first widely disruptive computer worm, which paralyzed several international computer networks in December 1987. The malware ran on the IBM VM/CMS operating system.

Written by a student at the Clausthal University of Technology in the REXX scripting language, it drew a crude Christmas tree as text graphics, then sent itself to each entry in the target's email contacts file. In this way it spread onto the European Academic Research Network (EARN), BITNET, and IBM's worldwide VNET. On all of these systems it caused massive disruption.

The core mechanism of the ILOVEYOU worm of 2000 was essentially the same as Christmas Tree, although it ran on PCs rather than mainframes, was spread over a different network, and was scripted using VBScript rather than REXX.

🔗 Computing 🔗 Computer Security 🔗 Computer Security/Computing 🔗 Computing/Software

In information security and programming, a buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations.

Buffers are areas of memory set aside to hold data, often while moving it from one section of a program to another, or between programs. Buffer overflows can often be triggered by malformed inputs; if one assumes all inputs will be smaller than a certain size and the buffer is created to be that size, then an anomalous transaction that produces more data could cause it to write past the end of the buffer. If this overwrites adjacent data or executable code, this may result in erratic program behavior, including memory access errors, incorrect results, and crashes.

Exploiting the behavior of a buffer overflow is a well-known security exploit. On many systems, the memory layout of a program, or the system as a whole, is well defined. By sending in data designed to cause a buffer overflow, it is possible to write into areas known to hold executable code and replace it with malicious code, or to selectively overwrite data pertaining to the program's state, therefore causing behavior that was not intended by the original programmer. Buffers are widespread in operating system (OS) code, so it is possible to make attacks that perform privilege escalation and gain unlimited access to the computer's resources. The famed Morris worm in 1988 used this as one of its attack techniques.

Programming languages commonly associated with buffer overflows include C and C++, which provide no built-in protection against accessing or overwriting data in any part of memory and do not automatically check that data written to an array (the built-in buffer type) is within the boundaries of that array. Bounds checking can prevent buffer overflows, but requires additional code and processing time. Modern operating systems use a variety of techniques to combat malicious buffer overflows, notably by randomizing the layout of memory, or deliberately leaving space between buffers and looking for actions that write into those areas ("canaries").

🔗 Biography 🔗 Computing 🔗 Mathematics 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory 🔗 Physics 🔗 Economics 🔗 Philosophy 🔗 Philosophy/Logic 🔗 Biography/science and academia 🔗 Philosophy/Philosophy of science 🔗 Philosophy/Contemporary philosophy 🔗 Military history/Military biography 🔗 Biography/military biography 🔗 History of Science 🔗 Computing/Computer science 🔗 Philosophy/Philosophers 🔗 Education 🔗 Hungary 🔗 Military history/World War II 🔗 Military history/Cold War 🔗 Physics/History 🔗 Physics/Biographies 🔗 Game theory 🔗 Eastern Europe

John von Neumann (; Hungarian: Neumann János Lajos, pronounced [ˈnɒjmɒn ˈjaːnoʃ ˈlɒjoʃ]; December 28, 1903 – February 8, 1957) was a Hungarian-American mathematician, physicist, computer scientist, engineer and polymath. Von Neumann was generally regarded as the foremost mathematician of his time and said to be "the last representative of the great mathematicians"; who integrated both pure and applied sciences.

He made major contributions to a number of fields, including mathematics (foundations of mathematics, functional analysis, ergodic theory, representation theory, operator algebras, geometry, topology, and numerical analysis), physics (quantum mechanics, hydrodynamics, and quantum statistical mechanics), economics (game theory), computing (Von Neumann architecture, linear programming, self-replicating machines, stochastic computing), and statistics.

He was a pioneer of the application of operator theory to quantum mechanics in the development of functional analysis, and a key figure in the development of game theory and the concepts of cellular automata, the universal constructor and the digital computer.

He published over 150 papers in his life: about 60 in pure mathematics, 60 in applied mathematics, 20 in physics, and the remainder on special mathematical subjects or non-mathematical ones. His last work, an unfinished manuscript written while he was in hospital, was later published in book form as The Computer and the Brain.

His analysis of the structure of self-replication preceded the discovery of the structure of DNA. In a short list of facts about his life he submitted to the National Academy of Sciences, he stated, "The part of my work I consider most essential is that on quantum mechanics, which developed in Göttingen in 1926, and subsequently in Berlin in 1927–1929. Also, my work on various forms of operator theory, Berlin 1930 and Princeton 1935–1939; on the ergodic theorem, Princeton, 1931–1932."

During World War II, von Neumann worked on the Manhattan Project with theoretical physicist Edward Teller, mathematician Stanisław Ulam and others, problem solving key steps in the nuclear physics involved in thermonuclear reactions and the hydrogen bomb. He developed the mathematical models behind the explosive lenses used in the implosion-type nuclear weapon, and coined the term "kiloton" (of TNT), as a measure of the explosive force generated.

After the war, he served on the General Advisory Committee of the United States Atomic Energy Commission, and consulted for a number of organizations, including the United States Air Force, the Army's Ballistic Research Laboratory, the Armed Forces Special Weapons Project, and the Lawrence Livermore National Laboratory. As a Hungarian émigré, concerned that the Soviets would achieve nuclear superiority, he designed and promoted the policy of mutually assured destruction to limit the arms race.

🔗 Computing 🔗 Computing/Software

"You aren't gonna need it" (YAGNI) is a principle of extreme programming (XP) that states a programmer should not add functionality until deemed necessary. XP co-founder Ron Jeffries has written: "Always implement things when you actually need them, never when you just foresee that you need them." Other forms of the phrase include "You aren't going to need it" and "You ain't gonna need it".