1.
Computer program
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A computer program is a collection of instructions that performs a specific task when executed by a computer. A computer requires programs to function, and typically executes the programs instructions in a processing unit. A computer program is written by a computer programmer in a programming language. From the program in its form of source code, a compiler can derive machine code—a form consisting of instructions that the computer can directly execute. Alternatively, a program may be executed with the aid of an interpreter. A part of a program that performs a well-defined task is known as an algorithm. A collection of programs, libraries and related data are referred to as software. Computer programs may be categorized along functional lines, such as software or system software. The earliest programmable machines preceded the invention of the digital computer, in 1801, Joseph-Marie Jacquard devised a loom that would weave a pattern by following a series of perforated cards. Patterns could be weaved and repeated by arranging the cards, in 1837, Charles Babbage was inspired by Jacquards loom to attempt to build the Analytical Engine. The names of the components of the device were borrowed from the textile industry. In the textile industry, yarn was brought from the store to be milled, the device would have had a store—memory to hold 1,000 numbers of 40 decimal digits each. Numbers from the store would then have then transferred to the mill. It was programmed using two sets of perforated cards—one to direct the operation and the other for the input variables, however, after more than 17,000 pounds of the British governments money, the thousands of cogged wheels and gears never fully worked together. During a nine-month period in 1842–43, Ada Lovelace translated the memoir of Italian mathematician Luigi Menabrea, the memoir covered the Analytical Engine. The translation contained Note G which completely detailed a method for calculating Bernoulli numbers using the Analytical Engine and this note is recognized by some historians as the worlds first written computer program. In 1936, Alan Turing introduced the Universal Turing machine—a theoretical device that can model every computation that can be performed on a Turing complete computing machine and it is a finite-state machine that has an infinitely long read/write tape. The machine can move the back and forth, changing its contents as it performs an algorithm
2.
Computer
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A computer is a device that can be instructed to carry out an arbitrary set of arithmetic or logical operations automatically. The ability of computers to follow a sequence of operations, called a program, such computers are used as control systems for a very wide variety of industrial and consumer devices. The Internet is run on computers and it millions of other computers. 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 speed, power, and versatility of computers has increased continuously and dramatically since then, conventionally, a modern computer consists of at least one processing element, typically a central processing unit, and some form of memory. The processing element carries out arithmetic and logical operations, and a sequencing, peripheral devices include input devices, output devices, and input/output devices that perform both functions. Peripheral devices allow information to be retrieved from an external source and this usage of the term referred to a person who carried out calculations or computations. The word continued with the same meaning until the middle of the 20th century, from the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations. The Online Etymology Dictionary gives the first attested use of computer in the 1640s, one who calculates, the Online Etymology Dictionary states that the use of the term to mean calculating machine is from 1897. The Online Etymology Dictionary indicates that the use of the term. 1945 under this name, theoretical from 1937, as Turing machine, devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. The earliest counting device was probably a form of tally stick, later record keeping aids throughout the Fertile Crescent included calculi which represented counts of items, probably livestock or grains, sealed in hollow unbaked clay containers. The use of counting rods is one example, the abacus was initially used for arithmetic tasks. The Roman abacus was developed from used in Babylonia as early as 2400 BC. Since then, many forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, the Antikythera mechanism is believed to be the earliest mechanical analog computer, according to Derek J. de Solla Price. It was designed to calculate astronomical positions and it was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to circa 100 BC
3.
Sun Microsystems
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Sun contributed significantly to the evolution of several key computing technologies, among them Unix, RISC processors, thin client computing, and virtualized computing. Sun was founded on February 24,1982, at its height, the Sun headquarters were in Santa Clara, California, on the former west campus of the Agnews Developmental Center. On January 27,2010, Oracle Corporation acquired Sun by for US$7.4 billion, other technologies include the Java platform, MySQL, and NFS. Sun was a proponent of open systems in general and Unix in particular, the initial design for what became Suns first Unix workstation, the Sun-1, was conceived by Andy Bechtolsheim when he was a graduate student at Stanford University in Palo Alto, California. Bechtolsheim originally designed the SUN workstation for the Stanford University Network communications project as a personal CAD workstation and it was designed around the Motorola 68000 processor with an advanced memory management unit to support the Unix operating system with virtual memory support. He built the first ones from spare parts obtained from Stanfords Department of Computer Science, on February 24,1982, Vinod Khosla, Andy Bechtolsheim, and Scott McNealy, all Stanford graduate students, founded Sun Microsystems. Bill Joy of Berkeley, a developer of the Berkeley Software Distribution. The Sun name is derived from the initials of the Stanford University Network, Sun was profitable from its first quarter in July 1982. By 1983 Sun was known for producing 68000-based systems with high-quality graphics that were the only computers other than DECs VAX to run 4. 2BSD and it licensed the computer design to other manufacturers, which typically used it to build Multibus-based systems running Unix from UniSoft. Suns initial public offering was in 1986 under the stock symbol SUNW, the symbol was changed in 2007 to JAVA, Sun stated that the brand awareness associated with its Java platform better represented the companys current strategy. Suns logo, which features four interleaved copies of the sun in the form of a rotationally symmetric ambigram, was designed by professor Vaughan Pratt. The initial version of the logo was orange and had the sides oriented horizontally and vertically, but it was rotated to stand on one corner and re-colored purple. In the dot-com bubble, Sun began making more money. It also began spending more, hiring workers and building itself out. Some of this was because of demand, but much was from web start-up companies anticipating business that would never happen. Sales in Suns important hardware division went into free-fall as customers closed shop, several quarters of steep losses led to executive departures, rounds of layoffs, and other cost cutting. In December 2001, the fell to the 1998, pre-bubble level of about $100. But it kept falling, faster than many other tech companies, a year later it had dipped below $10 but bounced back to $20
4.
Embedded system
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An embedded system is a computer system with a dedicated function within a larger mechanical or electrical system, often with real-time computing constraints. It is embedded as part of a device often including hardware. Embedded systems control many devices in use today. Ninety-eight percent of all microprocessors are manufactured as components of embedded systems, examples of properties of typically embedded computers when compared with general-purpose counterparts are low power consumption, small size, rugged operating ranges, and low per-unit cost. This comes at the price of limited processing resources, which make them more difficult to program. For example, intelligent techniques can be designed to power consumption of embedded systems. Modern embedded systems are based on microcontrollers, but ordinary microprocessors are also common. In either case, the processor used may be ranging from general purpose to those specialised in certain class of computations. A common standard class of dedicated processors is the signal processor. Since the embedded system is dedicated to tasks, design engineers can optimize it to reduce the size and cost of the product and increase the reliability. Some embedded systems are mass-produced, benefiting from economies of scale, complexity varies from low, with a single microcontroller chip, to very high with multiple units, peripherals and networks mounted inside a large chassis or enclosure. One of the very first recognizably modern embedded systems was the Apollo Guidance Computer, an early mass-produced embedded system was the Autonetics D-17 guidance computer for the Minuteman missile, released in 1961. When the Minuteman II went into production in 1966, the D-17 was replaced with a new computer that was the first high-volume use of integrated circuits. Since these early applications in the 1960s, embedded systems have come down in price and there has been a rise in processing power. An early microprocessor for example, the Intel 4004, was designed for calculators and other systems but still required external memory. By the early 1980s, memory, input and output system components had been integrated into the chip as the processor forming a microcontroller. Microcontrollers find applications where a computer would be too costly. A comparatively low-cost microcontroller may be programmed to fulfill the role as a large number of separate components
5.
Microcontroller
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A microcontroller is a small computer on a single integrated circuit. In modern terminology, it is a system on a chip or SoC, a microcontroller contains one or more CPUs along with memory and programmable input/output peripherals. Program memory in the form of Ferroelectric RAM, NOR flash or OTP ROM is also included on chip. Microcontrollers are designed for embedded applications, in contrast to the used in personal computers or other general purpose applications consisting of various discrete chips. Mixed signal microcontrollers are common, integrating analog components needed to control non-digital electronic systems, some microcontrollers may use four-bit words and operate at frequencies as low as 4 kHz, for low power consumption. Other microcontrollers may serve performance-critical roles, where they may need to act more like a signal processor, with higher clock speeds. The first microprocessor was the 4-bit Intel 4004 released in 1971, with the Intel 8008, however, both processors required external chips to implement a working system, raising total system cost, and making it impossible to economically computerize appliances. One book credits TI engineers Gary Boone and Michael Cochran with the creation of the first microcontroller in 1971. The result of their work was the TMS1000, which became available in 1974. It combined read-only memory, read/write memory, processor and clock on one chip and was targeted at embedded systems and it combined RAM and ROM on the same chip. This chip would find its way into one billion PC keyboards. At that time Intels President, Luke J. Valenter, stated that the microcontroller was one of the most successful in the companys history, most microcontrollers at this time had concurrent variants. One had an erasable EPROM program memory, with a transparent quartz window in the lid of the package to allow it to be erased by exposure to ultraviolet light, often used for prototyping. The PROM was of type of memory as the EPROM. The erasable versions required ceramic packages with quartz windows, making them more expensive than the OTP versions. The same year, Atmel introduced the first microcontroller using Flash memory, other companies rapidly followed suit, with both memory types. Cost has plummeted over time, with the cheapest 8-bit microcontrollers being available for under 0.25 USD in quantity in 2009, nowadays microcontrollers are cheap and readily available for hobbyists, with large online communities around certain processors. In the future, MRAM could potentially be used in microcontrollers as it has infinite endurance, in 2002, about 55% of all CPUs sold in the world were 8-bit microcontrollers and microprocessors
6.
Light-emitting diode
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A light-emitting diode is a two-lead semiconductor light source. It is a p–n junction diode, which emits light when activated, when a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light is determined by the band gap of the semiconductor. LEDs are typically small and integrated optical components may be used to shape the radiation pattern, appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. Infrared LEDs are still used as transmitting elements in remote-control circuits. The first visible-light LEDs were also of low intensity and limited to red, modern LEDs are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness. Early LEDs were often used as indicator lamps for electronic devices and they were soon packaged into numeric readouts in the form of seven-segment displays and were commonly seen in digital clocks. Recent developments in LEDs permit them to be used in environmental, LEDs have allowed new displays and sensors to be developed, while their high switching rates are also used in advanced communications technology. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes are now used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, as of 2017, LED lights home room lighting are as cheap or cheaper than compact fluorescent lamp sources of comparable output. They are also more energy efficient and, arguably, have fewer environmental concerns linked to their disposal. Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide, russian inventor Oleg Losev reported creation of the first LED in 1927. His research was distributed in Soviet, German and British scientific journals, rubin Braunstein of the Radio Corporation of America reported on infrared emission from gallium arsenide and other semiconductor alloys in 1955. Braunstein observed infrared emission generated by simple diode structures using gallium antimonide, GaAs, indium phosphide, in 1957, Braunstein further demonstrated that the rudimentary devices could be used for non-radio communication across a short distance. As noted by Kroemer Braunstein …had set up a simple optical communications link, the emitted light was detected by a PbS diode some distance away. This signal was fed into an amplifier and played back by a loudspeaker. Intercepting the beam stopped the music and we had a great deal of fun playing with this setup. This setup presaged the use of LEDs for optical communication applications, by October 1961, they had demonstrated efficient light emission and signal coupling between a GaAs p-n junction light emitter and an electrically-isolated semiconductor photodetector
7.
Linux
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Linux is a Unix-like computer operating system assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on September 17,1991 by Linus Torvalds, the Free Software Foundation uses the name GNU/Linux to describe the operating system, which has led to some controversy. Linux was originally developed for computers based on the Intel x86 architecture. Because of the dominance of Android on smartphones, Linux has the largest installed base of all operating systems. Linux is also the operating system on servers and other big iron systems such as mainframe computers. It is used by around 2. 3% of desktop computers, the Chromebook, which runs on Chrome OS, dominates the US K–12 education market and represents nearly 20% of the sub-$300 notebook sales in the US. Linux also runs on embedded systems – devices whose operating system is built into the firmware and is highly tailored to the system. This includes TiVo and similar DVR devices, network routers, facility automation controls, televisions, many smartphones and tablet computers run Android and other Linux derivatives. The development of Linux is one of the most prominent examples of free, the underlying source code may be used, modified and distributed—commercially or non-commercially—by anyone under the terms of its respective licenses, such as the GNU General Public License. Typically, Linux is packaged in a known as a Linux distribution for both desktop and server use. Distributions intended to run on servers may omit all graphical environments from the standard install, because Linux is freely redistributable, anyone may create a distribution for any intended use. The Unix operating system was conceived and implemented in 1969 at AT&Ts Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, first released in 1971, Unix was written entirely in assembly language, as was common practice at the time. Later, in a key pioneering approach in 1973, it was rewritten in the C programming language by Dennis Ritchie, the availability of a high-level language implementation of Unix made its porting to different computer platforms easier. Due to an earlier antitrust case forbidding it from entering the computer business, as a result, Unix grew quickly and became widely adopted by academic institutions and businesses. In 1984, AT&T divested itself of Bell Labs, freed of the legal obligation requiring free licensing, the GNU Project, started in 1983 by Richard Stallman, has the goal of creating a complete Unix-compatible software system composed entirely of free software. Later, in 1985, Stallman started the Free Software Foundation, by the early 1990s, many of the programs required in an operating system were completed, although low-level elements such as device drivers, daemons, and the kernel were stalled and incomplete. Linus Torvalds has stated that if the GNU kernel had been available at the time, although not released until 1992 due to legal complications, development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux. Torvalds has also stated that if 386BSD had been available at the time, although the complete source code of MINIX was freely available, the licensing terms prevented it from being free software until the licensing changed in April 2000
8.
Bell Labs
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Nokia Bell Labs is an American research and scientific development company, owned by Finnish company Nokia. Its headquarters are located in Murray Hill, New Jersey, in addition to laboratories around the rest of the United States. The historic laboratory originated in the late 19th century as the Volta Laboratory, Bell Labs was also at one time a division of the American Telephone & Telegraph Company, half-owned through its Western Electric manufacturing subsidiary. Eight Nobel Prizes have been awarded for work completed at Bell Laboratories, in 1880, the French government awarded Alexander Graham Bell the Volta Prize of 50,000 francs, approximately US$10,000 at that time for the invention of the telephone. Bell used the award to fund the Volta Laboratory in Washington, D. C. in collaboration with Sumner Tainter, the laboratory is also variously known as the Volta Bureau, the Bell Carriage House, the Bell Laboratory and the Volta Laboratory. The laboratory focused on the analysis, recording, and transmission of sound, Bell used his considerable profits from the laboratory for further research and education to permit the diffusion of knowledge relating to the deaf. This resulted in the founding of the Volta Bureau c,1887, located at Bells fathers house at 1527 35th Street in Washington, D. C. where its carriage house became their headquarters in 1889. In 1893, Bell constructed a new building, close by at 1537 35th St. specifically to house the lab, the building was declared a National Historic Landmark in 1972. In 1884, the American Bell Telephone Company created the Mechanical Department from the Electrical, the first president of research was Frank B. Jewett, who stayed there until 1940, ownership of Bell Laboratories was evenly split between AT&T and the Western Electric Company. Its principal work was to plan, design, and support the equipment that Western Electric built for Bell System operating companies and this included everything from telephones, telephone exchange switches, and transmission equipment. Bell Labs also carried out consulting work for the Bell Telephone Company, a few workers were assigned to basic research, and this attracted much attention, especially since they produced several Nobel Prize winners. Until the 1940s, the principal locations were in and around the Bell Labs Building in New York City. Of these, Murray Hill and Crawford Hill remain in existence, the largest grouping of people in the company was in Illinois, at Naperville-Lisle, in the Chicago area, which had the largest concentration of employees prior to 2001. Since 2001, many of the locations have been scaled down or closed. The Holmdel site, a 1.9 million square foot structure set on 473 acres, was closed in 2007, the mirrored-glass building was designed by Eero Saarinen. In August 2013, Somerset Development bought the building, intending to redevelop it into a commercial and residential project. The prospects of success are clouded by the difficulty of readapting Saarinens design and by the current glut of aging, eight Nobel Prizes have been awarded for work completed at Bell Laboratories
9.
Field-programmable gate array
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A field-programmable gate array is an integrated circuit designed to be configured by a customer or a designer after manufacturing – hence field-programmable. The FPGA configuration is generally specified using a description language. Logic blocks can be configured to perform complex functions, or merely simple logic gates like AND. In most FPGAs, logic blocks also include elements, which may be simple flip-flops or more complete blocks of memory. Contemporary field-programmable gate arrays have large resources of logic gates and RAM blocks to implement complex digital computations, as FPGA designs employ very fast I/Os and bidirectional data buses, it becomes a challenge to verify correct timing of valid data within setup time and hold time. Floor planning enables resources allocation within FPGAs to meet time constraints. FPGAs can be used to implement any logical function that an ASIC could perform, some FPGAs have analog features in addition to digital functions. Fairly common are differential comparators on input pins designed to be connected to differential signaling channels, the FPGA industry sprouted from programmable read-only memory and programmable logic devices. PROMs and PLDs both had the option of being programmed in batches in a factory or in the field, however, programmable logic was hard-wired between logic gates. In the late 1980s, the Naval Surface Warfare Center funded an experiment proposed by Steve Casselman to develop a computer that would implement 600,000 reprogrammable gates, Casselman was successful and a patent related to the system was issued in 1992. Some of the foundational concepts and technologies for programmable logic arrays, gates. Xilinx co-founders Ross Freeman and Bernard Vonderschmitt invented the first commercially viable field-programmable gate array in 1985 – the XC2064, the XC2064 had programmable gates and programmable interconnects between gates, the beginnings of a new technology and market. The XC2064 had 64 configurable logic blocks, with two three-input lookup tables, more than 20 years later, Freeman was entered into the National Inventors Hall of Fame for his invention. Altera and Xilinx continued unchallenged and quickly grew from 1985 to the mid-1990s, by 1993, Actel was serving about 18 percent of the market. By 2010, Altera, Actel and Xilinx together represented approximately 77 percent of the FPGA market, the 1990s were an explosive period of time for FPGAs, both in sophistication and the volume of production. In the early 1990s, FPGAs were primarily used in telecommunications, by the end of the decade, FPGAs found their way into consumer, automotive, and industrial applications. This work mirrors the architecture by Ron Perlof and Hana Potash of Burroughs Advanced Systems Group which combined a reconfigurable CPU architecture on a chip called the SB24. That work was done in 1982, the Atmel FPSLIC is another such device, which uses an AVR processor in combination with Atmels programmable logic architecture
10.
Ubuntu (operating system)
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Ubuntu is published by Canonical Ltd, who offer commercial support. It uses Unity as its user interface for the desktop. Ubuntu is the most popular operating system running in hosted environments, so–called clouds, development of Ubuntu is led by UK-based Canonical Ltd. a company of South African entrepreneur Mark Shuttleworth. Canonical generates revenue through the sale of technical support and other related to Ubuntu. The Ubuntu project is committed to the principles of open-source software development, people are encouraged to use free software, study how it works, improve upon it. Ubuntu is built on Debians architecture and infrastructure, to provide Linux server, desktop, phone, tablet, the first release was in October 2004. Starting with Ubuntu 6.06, every release, one release every two years, receives long-term support. Long-term support includes updates for new hardware, security patches and updates to the Ubuntu stack. The first LTS releases were supported for three years on the desktop and five years on the server, since Ubuntu 12.04 LTS, LTS releases get regular point releases with support for new hardware and integration of all the updates published in that series to date. Ubuntu packages are based on packages from Debians unstable branch, both distributions use Debians deb package format and package management tools. Debian and Ubuntu packages are not necessarily compatible with each other, however. Many Ubuntu developers are also maintainers of key packages within Debian, Ubuntu cooperates with Debian by pushing changes back to Debian, although there has been criticism that this does not happen often enough. Ian Murdock, the founder of Debian, had expressed concern about Ubuntu packages potentially diverging too far from Debian to remain compatible, before release, packages are imported from Debian unstable continuously and merged with Ubuntu-specific modifications. One month before release, imports are frozen, and packagers then work to ensure that the frozen features interoperate well together, Ubuntu is currently funded by Canonical Ltd. On 8 July 2005, Mark Shuttleworth and Canonical announced the creation of the Ubuntu Foundation, the purpose of the foundation is to ensure the support and development for all future versions of Ubuntu. Mark Shuttleworth describes the goal as to ensure the continuity of the Ubuntu project. On 12 March 2009, Ubuntu announced developer support for 3rd-party cloud management platforms, Unity has become the default GUI for Ubuntu Desktop, although following the release of Ubuntu 17.10 it will move to the GNOME3 desktop instead as work on Unity ends. A default installation of Ubuntu contains a range of software that includes LibreOffice, Firefox, Thunderbird, Transmission
11.
Light painting
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The technique is used for both scientific and artistic purposes, as well as in commercial photography. Light painting dates back to 1889 when Étienne-Jules Marey and Georges Demeny traced human motion in the first known light painting “Pathological Walk From in Front”, man Ray, in his 1935 series Space Writing, was the first known art photographer to use the technique. Photographer Barbara Morgan began making paintings in 1940. In 1949 Pablo Picasso was visited by Gjon Mili, a photographer and lighting innovator, immediately Picasso started making images in the air with a small flashlight in a dark room. This series of photos became known as Picassos light drawings and he produced a series Schwingungsfigur of complex linear meshes, often with moiré effects, using a point-source light on a pendulum. During the 1970s and 80s Eric Staller used this technology for numerous projects that were called Light Drawings. Light paintings up to 1976 are classified as light drawings, in 1977 Dean Chamberlain gave birth to light painting with his image Polyethylene Bags On Chaise Longue at The Rochester Institute of Technology. Dean Chamberlain was the first artist to dedicate his entire body of work to the light painting art form, the artist photographer Jacques Pugin made several series of images with the light drawing technique in 1979. Picasso and Milis images should be regarded as some of the first light drawings, now, with modern light painting, one uses more frequently choreography and performance to photograph and organize. Since the 1980s, Vicki DaSilva has been working exclusively in light painting, in 1980, Vicki DaSilva started making deliberate text light graffiti works, the first being Cash. She continued these light graffiti photographs throughout the 1980s and eventually started using 4 foot fluorescent bulbs hooked up to pulley systems to create sheets of light. In the early 2000s she began making work with 8 foot fluorescent lamps, holding the lamp vertically, Light painting requires a slow shutter speed, usually at least a second in duration. Light paintings can be created using a webcam, the painted image can already be seen while drawing by using a monitor or projector. Another technique is the projection of images on to irregular surfaces, a photograph or other fixed portrayal of the resulting image is then made. Kinetic light painting is achieved by moving the camera, and is the antithesis of traditional photography, at night, or in a dark room, the camera can be removed from the tripod and used like a paintbrush. An example is using the sky as the canvas, the camera as the brush. Putting energy into moving the camera by stroking lights, making patterns, a variety of light sources can be used, ranging from simple flashlights to dedicated devices like the Hosemaster, which uses a fiber optic light pen. Other sources of light including candles, matches, fireworks, lighter flints, glowsticks, the PixelStick offer users the ability to control their light source in order to create images from letters to pictures that they have imported
12.
Debian
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The Debian Project was first announced in 1993 by Ian Murdock, Debian 0.01 was released on September 15,1993, and the first stable release was made in 1996. The Debian stable release branch is one of the most popular for personal computers and network servers, new distributions are updated continually, and the next candidate is released after a time-based freeze. As one of the earliest Operating Systems based on the Linux kernel and this decision drew the attention and support of the Free Software Foundation, which sponsored the project for one year from November 1994 to November 1995. Upon the ending of the sponsorship, the Debian Project formed the non-profit organisation Software in the Public Interest, while Debians main port, Debian GNU/Linux, uses the Linux kernel, other ports exist based on BSD kernels and the HURD microkernel. All use the GNU userland and the GNU C library, Debian has access to online repositories that contain over 50,000 software packages making it one of the largest software compilations. Debian officially contains only free software, but non-free software can be downloaded from the Debian repositories, Debian includes popular free programs such as LibreOffice, Firefox web browser, Evolution mail, K3b disc burner, VLC media player, GIMP image editor, and Evince document viewer. Debian is a choice for web servers. Debian supports Linux officially, offered kFreeBSD for version 7 but not 8, GNU/kFreeBSD was released as a technology preview for IA-32 and x86-64 architectures, and lacked the amount of software available in Debians Linux distribution. Official support for kFreeBSD was removed for version 8, which did not provide a kFreeBSD-based distribution, several flavors of the Linux kernel exist for each port. For example, the port has flavors for IA-32 PCs supporting Physical Address Extension and real-time computing, for older PCs. The Linux kernel does not officially contain firmware without sources, although such firmware is available in non-free packages, Debian offers DVD and CD images for installation that can be downloaded using BitTorrent or jigdo. Physical disks can also be bought from retailers, Debian offers different network installation methods. A minimal install of Debian is available via the netinst CD, whereby Debian is installed with just a base, another option is to boot the installer from the network. Installation images are hybrid on some architectures and can be used to create a bootable USB drive, the default bootstrap loader is GNU GRUB version 2, though the package name is simply grub, while version 1 was renamed to grub-legacy. This conflicts with e. g. Fedora, where grub version 2 is named grub2, the default desktop may be chosen from the DVD boot menu among GNOME, KDE Software Compilation, Xfce and LXDE, and from special disc 1 CDs. Debian offers CD images specifically built for GNOME, KDE Software Compilation, Xfce, MATE is officially supported, while Cinnamon support was added with Debian 8.0 Jessie. Less common window managers such as Enlightenment, Openbox, Fluxbox, IceWM, Window Maker, the default desktop environment of version 7.0 Wheezy was temporarily switched to Xfce, because GNOME3 did not fit on the first CD of the set. The default for the version 8.0 Jessie was changed again to Xfce in November 2013, Debian releases live install images for CDs, DVDs and USB thumb drives, for IA-32 and x86-64 architectures, and with a choice of desktop environments
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List of hello world programs at Wikibooks
