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π Computer
A computer is a machine that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. Modern computers have the ability to follow generalized sets of operations, called programs. These programs enable computers to perform an extremely wide range of tasks. A "complete" computer including the hardware, the operating system (main software), and peripheral equipment required and used for "full" operation can be referred to as a computer system. This term may as well be used for a group of computers that are connected and work together, in particular a computer network or computer cluster.
Computers are used as control systems for a wide variety of industrial and consumer devices. This includes simple special purpose devices like microwave ovens and remote controls, factory devices such as industrial robots and computer-aided design, and also general purpose devices like personal computers and mobile devices such as smartphones. The Internet is run on computers and it connects hundreds of millions of other computers and their users.
Early computers were only conceived as calculating devices. Since ancient times, simple manual devices like the abacus aided people in doing calculations. Early in the Industrial Revolution, some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century. The first digital electronic calculating machines were developed during World War II. The first semiconductor transistors in the late 1940s were followed by the silicon-based MOSFET (MOS transistor) and monolithic integrated circuit (IC) chip technologies in the late 1950s, leading to the microprocessor and the microcomputer revolution in the 1970s. The speed, power and versatility of computers have been increasing dramatically ever since then, with MOS transistor counts increasing at a rapid pace (as predicted by Moore's law), leading to the Digital Revolution during the late 20th to early 21st centuries.
Conventionally, a modern computer consists of at least one processing element, typically a central processing unit (CPU) in the form of a metal-oxide-semiconductor (MOS) microprocessor, along with some type of computer memory, typically MOS semiconductor memory chips. The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices include input devices (keyboards, mice, joystick, etc.), output devices (monitor screens, printers, etc.), and input/output devices that perform both functions (e.g., the 2000s-era touchscreen). Peripheral devices allow information to be retrieved from an external source and they enable the result of operations to be saved and retrieved.
π Iron law of prohibition
The iron law of prohibition is a term coined by Richard Cowan in 1986 which posits that as law enforcement becomes more intense, the potency of prohibited substances increases. Cowan put it this way: "the harder the enforcement, the harder the drugs."
This law is an application of the AlchianβAllen effect; Libertarian judge James P. Gray calls the law the "cardinal rule of prohibition", and notes that is a powerful argument for the legalization of drugs. It is based on the premise that when drugs or alcohol are prohibited, they will be produced in black markets in more concentrated and powerful forms, because these more potent forms offer better efficiency in the business modelβthey take up less space in storage, less weight in transportation, and they sell for more money. Economist Mark Thornton writes that the iron law of prohibition undermines the argument in favor of prohibition, because the higher potency forms are less safe for the consumer.
Discussed on
- "Iron law of prohibition" | 2017-03-12 | 143 Upvotes 74 Comments
π Pop pop boat
A pop-pop boat is a toy with a very simple steam engine without moving parts, typically powered by a candle or vegetable oil burner. The name comes from the noise made by some versions of the boats. Other names are putt-putt boat, crazy boat, flash-steamer, hot-air-boat, pulsating water engine boat. Around the world they may be called Can-Can-boot, Knatterboot, toc-toc, Puf-Puf boat, Poof Poof craft, Phut-Phut, or Pouet-Pouet.
π Background of .plan files: the 1977 Finger Protocol
In computer networking, the Name/Finger protocol and the Finger user information protocol are simple network protocols for the exchange of human-oriented status and user information.
Discussed on
- "Background of .plan files: the 1977 Finger Protocol" | 2011-12-18 | 19 Upvotes 7 Comments
π The Interesting Number Paradox
The interesting number paradox is a semi-humorous paradox which arises from the attempt to classify every natural number as either "interesting" or "uninteresting". The paradox states that every natural number is interesting. The "proof" is by contradiction: if there exists a non-empty set of uninteresting natural numbers, there would be a smallest uninteresting number β but the smallest uninteresting number is itself interesting because it is the smallest uninteresting number, thus producing a contradiction.
In a discussion between the mathematicians G. H. Hardy and Srinivasa Ramanujan about interesting and uninteresting numbers, Hardy remarked that the number 1729 of the taxicab he had ridden seemed "rather a dull one", and Ramanujan immediately answered that it is interesting, being the smallest number that is the sum of two cubes in two different ways.
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- "The Interesting Number Paradox" | 2009-11-14 | 65 Upvotes 9 Comments
π Kowloon Walled City
Kowloon Walled City was an ungoverned, densely populated settlement in Kowloon City, Hong Kong. Originally a Chinese military fort, the Walled City became an enclave after the New Territories were leased to the UK by China in 1898. Its population increased dramatically following the Japanese occupation of Hong Kong during World War II. By 1990, the walled city contained 50,000 residents within its 2.6-hectare (6.4-acre) borders. From the 1950s to the 1970s, it was controlled by local triads and had high rates of prostitution, gambling, and drug abuse.
In January 1987, the Hong Kong municipal government announced plans to demolish the walled city. After an arduous eviction process, demolition began in March 1993 and was completed in April 1994. Kowloon Walled City Park opened in December 1995 and occupies the area of the former Walled City. Some historical artefacts from the walled city, including its yamen building and remnants of its southern gate, have been preserved there.
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- "Kowloon Walled City" | 2017-12-21 | 90 Upvotes 25 Comments
π Risch Algorithm for Symbolic Integration
In symbolic computation (or computer algebra), at the intersection of mathematics and computer science, the Risch algorithm is an algorithm for indefinite integration. It is used in some computer algebra systems to find antiderivatives. It is named after the American mathematician Robert Henry Risch, a specialist in computer algebra who developed it in 1968.
The algorithm transforms the problem of integration into a problem in algebra. It is based on the form of the function being integrated and on methods for integrating rational functions, radicals, logarithms, and exponential functions. Risch called it a decision procedure, because it is a method for deciding whether a function has an elementary function as an indefinite integral, and if it does, for determining that indefinite integral.
The complete description of the Risch algorithm takes over 100 pages. The RischβNorman algorithm is a simpler, faster, but less powerful variant that was developed in 1976 by Arthur Norman.
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- "Risch Algorithm for Symbolic Integration" | 2019-03-02 | 40 Upvotes 4 Comments
- "Did you know that there's an algorithm for symbolic integration that always works?" | 2009-05-01 | 50 Upvotes 16 Comments
π Seki Takakazu
Seki Takakazu (ι’ εε, 1642 β December 5, 1708), also known as Seki KΕwa (ι’ εε), was a Japanese mathematician and author of the Edo period.
Seki laid foundations for the subsequent development of Japanese mathematics known as wasan; and he has been described as "Japan's Newton".
He created a new algebraic notation system and, motivated by astronomical computations, did work on infinitesimal calculus and Diophantine equations. A contemporary of German polymath mathematician and philosopher Gottfried Leibniz and British mathematician Isaac Newton, Seki's work was independent. His successors later developed a school dominant in Japanese mathematics until the end of the Edo period.
While it is not clear how much of the achievements of wasan are Seki's, since many of them appear only in writings of his pupils, some of the results parallel or anticipate those discovered in Europe. For example, he is credited with the discovery of Bernoulli numbers. The resultant and determinant (the first in 1683, the complete version no later than 1710) are attributed to him. These achievements are astonishing, considering that Japanese mathematics before his appearance was at such a primitive stage. For example, comprehensive introduction of 13th century Chinese algebra was made as late as 1671, by Kazuyuki Sawaguchi.
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- "Seki Takakazu" | 2019-06-21 | 84 Upvotes 12 Comments
π Linux Router Project
The Linux Router Project (LRP) is a now defunct networking-centric micro Linux distribution. The released versions of LRP were small enough to fit on a single 1.44MB floppy disk, and made building and maintaining routers, access servers, thin servers, thin clients, network appliances, and typically embedded systems next to trivial.
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- "Linux Router Project" | 2024-02-25 | 24 Upvotes 1 Comments
π Tennis for Two was an electronic game developed in 1958 on an analog computer
Tennis for Two (also known as Computer Tennis) is a sports video game, which simulates a game of tennis, and was one of the first games developed in the early history of video games. American physicist William Higinbotham designed the game in 1958 for display at the Brookhaven National Laboratory's annual public exhibition after learning that the government research institution's Donner Model 30 analog computer could simulate trajectories with wind resistance. He designed the game, displayed on an oscilloscope and played with two custom aluminum controllers, in a few hours, after which he and technician Robert V. Dvorak built it over three weeks. The game's visuals show a representation of a tennis court viewed from the side, and players adjust the angle of their shots with a knob on their controller and try to hit the ball over the net by pressing a button.
The game was very popular during the three-day exhibition, with players lining up to see the game, especially high school students. It was shown again the following year with a larger oscilloscope screen and a more complicated design that could simulate different gravity levels. It was then dismantled and largely forgotten until the late 1970s when Higinbotham testified in court about the game during lawsuits between Magnavox and Ralph H. Baer over video game patents. Since then, it has been celebrated as one of the earliest video games, and Brookhaven has made recreations of the original device. Under some definitions Tennis for Two is considered the first video game, as while it did not include any technological innovations over prior games, it was the first computer game to be created purely as an entertainment product rather than for academic research or commercial technology promotion.
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- "Tennis for Two was an electronic game developed in 1958 on an analog computer" | 2015-12-31 | 30 Upvotes 10 Comments