1.
Newline
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In computing, a newline, also known as a line ending, end of line, or line break, is a special character or sequence of characters signifying the end of a line of text and the start of a new line. The actual codes representing a newline vary across operating systems, which can be a problem when exchanging text files between systems with different newline representations, the concepts of line feed and carriage return are closely associated, and can be considered either separately or together. In the physical media of typewriters and printers, two axes of motion, down and across, are needed to create a new line on the page. Although the design of a machine must consider them separately, the logic of software can combine them together as one event. This is why a newline in character encoding can be defined as LF, some character sets provide a separate newline character code. EBCDIC, for example, provides an NL character code in addition to the CR, Unicode, in addition to providing the ASCII CR and LF control codes, also provides a next line control code, as well as control codes for line separator and paragraph separator markers. Two ways to view newlines, both of which are self-consistent, are that newlines either separate lines or that they terminate lines, if a newline is considered a separator, there will be no newline after the last line of a file. Some programs have problems processing the last line of a file if it is not terminated by a newline, on the other hand, programs that expect newline to be used as a separator will interpret a final newline as starting a new line. Conversely, if a newline is considered a terminator, all lines including the last are expected to be terminated by a newline. In many applications a separate character called manual line break exists for forcing line breaks inside a single paragraph. The glyph for the character for a hard return is usually a pilcrow. Some rare systems, such as QNX before version 4, used the ASCII RS character as the newline character, EBCDIC systems—mainly IBM mainframe systems, including z/OS and i5/OS —use NL as the character combining the functions of line-feed and carriage-return. The equivalent UNICODE character is called NEL, note that EBCDIC also has control characters called CR and LF, but the numerical value of LF differs from the one used by ASCII. Additionally, some EBCDIC variants also use NL but assign a different numeric code to the character, operating systems for the CDC6000 series defined a newline as two or more zero-valued six-bit characters at the end of a 60-bit word. Some configurations also defined a character as a colon character. ZX80 and ZX81, home computers from Sinclair Research Ltd, used a specific character set with code NEWLINE as the newline character. OpenVMS uses a file system, which stores text files as one record per line. In most file formats, no line terminators are actually stored, the records themselves could contain the same line terminator characters, which could either be considered a feature or a nuisance depending on the application
2.
Typewriter
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A typewriter is a mechanical or electromechanical machine for writing characters similar to those produced by printers movable type. A typewriter operates by means of keys that strike a ribbon to transmit ink or carbon impressions onto paper, typically, a single character is printed on each key press. The machine prints characters by making ink impressions of type elements similar to the used in movable type letterpress printing. At the end of the century, the term typewriter was also applied to a person who used a typing machine. After its invention in the 1860s, the quickly became an indispensable tool for practically all writing other than personal handwritten correspondence. It was widely used by writers, in offices. As with the automobile, telephone, and telegraph, a number of people contributed insights, historians have estimated that some form of typewriter was invented 52 times as thinkers tried to come up with a workable design. Some of the early typing instruments, In 1575 an Italian printmaker, Francesco Rampazzetto, invented the scrittura tattile, in 1714, Henry Mill obtained a patent in Britain for a machine that, from the patent, appears to have been similar to a typewriter. In 1802 Italian Agostino Fantoni developed a particular typewriter to enable his blind sister to write, in 1808 Italian Pellegrino Turri invented a typewriter. He also invented carbon paper to provide the ink for his machine, in 1823 Italian Pietro Conti di Cilavegna invented a new model of typewriter, the tachigrafo, also known as tachitipo. In 1829, William Austin Burt patented a machine called the Typographer which, the Science Museum describes it merely as the first writing mechanism whose invention was documented, but even that claim may be excessive, since Turris invention pre-dates it. Even in the hands of its inventor, this machine was slower than handwriting, Burt and his promoter John D. Sheldon never found a buyer for the patent, so the invention was never commercially produced, because the typographer used a dial, rather than keys, to select each character, it was called an index typewriter rather than a keyboard typewriter. Index typewriters of that era resemble the squeeze-style embosser from the 1960s more than they resemble the modern keyboard typewriter, by the mid-19th century, the increasing pace of business communication had created a need for mechanization of the writing process. Stenographers and telegraphers could take down information at rates up to 130 words per minute, from 1829 to 1870, many printing or typing machines were patented by inventors in Europe and America, but none went into commercial production. Charles Thurber developed multiple patents, of which his first in 1843 was developed as an aid to the blind, in 1855, the Italian Giuseppe Ravizza created a prototype typewriter called Cembalo scrivano o macchina da scrivere a tasti. It was a machine that let the user see the writing as it was typed. In 1861, Father Francisco João de Azevedo, a Brazilian priest, made his own typewriter with basic materials and tools, such as wood, in that same year the Brazilian emperor D
3.
IBM Electric typewriter
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The IBM Electric typewriters were a series of electric typewriters that IBM manufactured, starting in the mid-1930s. They used the moving carriage and typebar mechanism, as opposed to the fixed carriage and type ball used in the IBM Selectric. After 1944, each came in both Standard and Executive versions, the latter featuring proportional spacing. IBM typewriters had one feature lacking in many mechanical typewriters, the top row bore the digits 1234567890, the IBM design obviated substitutions taught by many typing instructors, o or O for 0, l for 1. These substitutions were easily identified when compared to an adjacent line typed with the keys and encouraged typists to confuse letters and numbers. The IBM Electromatic typewriter was the first electric typewriter to enjoy commercial success. Unlike the later IBM Selectric typewriter, this model used a conventional moving carriage. The history of the Electromatic goes back to 1924, when the North East Electric Company received patent rights for the roller from James Smathers. At that time, the company was selling electric motors, and they reached an arrangement with Remington, securing a contract for 2,500 machines in 1925. Electric manufactured the motor and power-roller base, the typewriter portion was made by Remington, based on its model Number 12. Remington had to do more than attach its typewriter to the base. All the units manufactured sold quickly and Remington wanted to continue the relationship, according to Darryl Rehr, in his 1997 book, Antique Typewriters & Office Collectibles, Remington claimed. They could sell as many as N. E, Electric on a contract, however, came at a time when Remington was unable to make such a commitment, so the Remington Electric went out of production. Electric Company then developed and produced the Electromatic, placing it on the market in 1929, after passing through the hands of General Motors, it became The Electromatic Typewriter Co. IBM acquired the assets of Electromatic Typewriters, Inc. of Rochester, N. Y. in 1933 and invested $1 million in redesigning their product and setting up service centers. The new IBMs Model 01 was introduced in 1935 and became the first successful electric typewriter in the U. S. according to IBM. Major model introductions included, In the 1950s, modified versions of the A, B. The IBM Selectric typewriter, introduced in 1961, was easier to interface to a computer and was favored in new designs, such as the IBM1130 computer and the IBM1050 terminal
4.
Underwood Typewriter Company
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The Underwood Typewriter Company was a manufacturer of typewriters headquartered in New York City, New York. Underwood produced what is considered the first widely successful, modern typewriter, by 1939, Underwood had produced five million machines. From 1874, the Underwood family made typewriter ribbon and carbon paper, when Remington decided to start producing ribbons themselves, the Underwoods opted to manufacture typewriters. The original Underwood typewriter was invented by German-American Franz Xaver Wagner, Underwood supported Wagner and bought the company, recognising the importance of the machine. 2s, made between 1896 and 1900, had Wagner Typewriter Co. printed on the back, the Underwood No.5 launched in 1900 has been described as the first truly modern typewriter. Two million had sold by the early 1920s, and its sales “were equal in quantity to all of the other firms in the typewriter industry combined”. When the company was in its heyday as the worlds largest typewriter manufacturer, its factory at Hartford, Underwood started adding addition and subtraction devices to their typewriters in about 1910. Philip Dakin Wagoner was appointed president of the Elliott-Fisher Company after World War I, Elliott-Fisher became the parent of the Underwood Typewriter Company and the Sundstrand Corporation. In 1927 Wagoner reorganized the company into Underwood-Elliott-Fisher, which became the Underwood Corporation. The reorganization was completed in December 1927, John Thomas Underwood was elected chairman and Wagoner president of Underwood Elliott-Fisher. In the years before World War II, Underwood built the worlds largest type writer in an attempt to promote itself, the typewriter was on display at Garden Pier in Atlantic City, New Jersey for several years and attracted large crowds. Often, Underwood would have a woman sitting on each of the large keys. The enormous typewriter was scrapped for metal when the war started, during World War II Underwood produced M1 carbines. In 1945 Wagoner was elected chairman of the board of Underwood, the Underwood name last appeared on Olivetti portable typewriters produced in Spain in the 80s. The Between the Lions episode Clickety Clack, Clickety Clack used an Underwood typewriter, in the 1991 Coen brothers film Barton Fink, John Turturros character Barton uses an Underwood typewriter in response to Jack Warners comment that screenwriters are Schmucks with Underwoods. Warner In the 2000 film He Died with a Felafel in His Hand directed by Richard Lowenstein, in the 2002 Steven Spielberg film Catch Me If You Can, Carl Hanratty shows Frank Abagnale a forged check, which he says was made with a stencil machine and an Underwood. An Underwood typewriter is featured on Fionn Regans 2006 album The End of History, an Underwood typewriter is used by the main character in the 2001 musical film Moulin Rouge. William Faulkner, F. Scott Fitzgerald, Ernest Hemingway, Jack Kerouac used an Underwood Portable Typewriter when he wrote On the Road
5.
IBM Selectric typewriter
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The IBM Selectric typewriter was a highly successful model line of electric typewriters introduced by IBM on 31 July 1961. The Selectric also replaced the traditional typewriters moving carriage with a roller that stayed in position while the typeball. The Selectric mechanism was notable for using internal mechanical binary coding, Selectrics and their descendants eventually captured 75 percent of the United States market for electric typewriters used in business. IBM replaced the Selectric line with the IBM Wheelwriter in 1984, the Selectric typewriter was introduced on 23 July 1961. Its industrial design is credited to influential American designer Eliot Noyes, Noyes had worked on a number of design projects for IBM, prior to his work on the Selectric, he had been commissioned in 1956 by Thomas J. Watson, Jr. The Selectric remained unchanged until 1971 when the Selectric II was introduced, the original design was thereafter referred to as the Selectric I. These machines used the same 88-character typing elements, separate typeballs were available for each pitch. The Selectric II had a lever that allowed characters to be shifted up to a space to the left. This option was only on dual pitch models. Stylistically, the Selectric II was squarer at the corners, whereas the Selectric I was rounder, in 1973 the Correcting Selectric II was announced. It added an internal correction feature to the Selectric II, intended to eliminate the need for typists to use cover-up tape, white-out correction fluid, the carriage on this machine held both the main typing ribbon cartridge and two small spools for a correction ribbon. A new ribbon type, the Correctable Film ribbon, was introduced at the same time and this produced typing quality equal to the carbon film ribbon, but with a pigment designed to be easily removable from paper. There were two types of correction tapes, The transparent and slightly adhesive Lift-Off tape, or the white Cover-Up tape, the correction tape was changed independently from the typing ribbon. The typist would press the key and then re-type the erroneous character, either lifting it off of the page or covering it with white-out powder. Any number of mistakes could be corrected this way, but the process was entirely manual, in 1964 IBM introduced the Magnetic Tape Selectric Typewriter and in 1969, a Magnetic Card Selectric Typewriter. These were sometimes referred to as the MT/ST and MC/ST, respectively, the MC/ST was also available in a communicating version that could emulate an IBM2741 terminal or run its native Correspondence Code. These featured electronically interfaced typing mechanisms and keyboards and a storage device for recording, editing. These machines were among the first to word processing capability in any form
6.
Unicode
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Unicode is a computing industry standard for the consistent encoding, representation, and handling of text expressed in most of the worlds writing systems. As of June 2016, the most recent version is Unicode 9.0, the standard is maintained by the Unicode Consortium. Unicodes success at unifying character sets has led to its widespread, the standard has been implemented in many recent technologies, including modern operating systems, XML, Java, and the. NET Framework. Unicode can be implemented by different character encodings, the most commonly used encodings are UTF-8, UTF-16 and the now-obsolete UCS-2. UTF-8 uses one byte for any ASCII character, all of which have the same values in both UTF-8 and ASCII encoding, and up to four bytes for other characters. UCS-2 uses a 16-bit code unit for each character but cannot encode every character in the current Unicode standard, UTF-16 extends UCS-2, using one 16-bit unit for the characters that were representable in UCS-2 and two 16-bit units to handle each of the additional characters. Many traditional character encodings share a common problem in that they allow bilingual computer processing, Unicode, in intent, encodes the underlying characters—graphemes and grapheme-like units—rather than the variant glyphs for such characters. In the case of Chinese characters, this leads to controversies over distinguishing the underlying character from its variant glyphs. In text processing, Unicode takes the role of providing a unique code point—a number, in other words, Unicode represents a character in an abstract way and leaves the visual rendering to other software, such as a web browser or word processor. This simple aim becomes complicated, however, because of concessions made by Unicodes designers in the hope of encouraging a more rapid adoption of Unicode, the first 256 code points were made identical to the content of ISO-8859-1 so as to make it trivial to convert existing western text. For other examples, see duplicate characters in Unicode and he explained that he name Unicode is intended to suggest a unique, unified, universal encoding. In this document, entitled Unicode 88, Becker outlined a 16-bit character model, Unicode could be roughly described as wide-body ASCII that has been stretched to 16 bits to encompass the characters of all the worlds living languages. In a properly engineered design,16 bits per character are more than sufficient for this purpose, Unicode aims in the first instance at the characters published in modern text, whose number is undoubtedly far below 214 =16,384. By the end of 1990, most of the work on mapping existing character encoding standards had been completed, the Unicode Consortium was incorporated in California on January 3,1991, and in October 1991, the first volume of the Unicode standard was published. The second volume, covering Han ideographs, was published in June 1992, in 1996, a surrogate character mechanism was implemented in Unicode 2.0, so that Unicode was no longer restricted to 16 bits. The Microsoft TrueType specification version 1.0 from 1992 used the name Apple Unicode instead of Unicode for the Platform ID in the naming table, Unicode defines a codespace of 1,114,112 code points in the range 0hex to 10FFFFhex. Normally a Unicode code point is referred to by writing U+ followed by its hexadecimal number, for code points in the Basic Multilingual Plane, four digits are used, for code points outside the BMP, five or six digits are used, as required. Code points in Planes 1 through 16 are accessed as surrogate pairs in UTF-16, within each plane, characters are allocated within named blocks of related characters
7.
Computing
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Computing is any goal-oriented activity requiring, benefiting from, or creating a mathematical sequence of steps known as an algorithm — e. g. through computers. The field of computing includes computer engineering, software engineering, computer science, information systems, the ACM Computing Curricula 2005 defined computing as follows, In a general way, we can define computing to mean any goal-oriented activity requiring, benefiting from, or creating computers. For example, an information systems specialist will view computing somewhat differently from a software engineer, regardless of the context, doing computing well can be complicated and difficult. Because society needs people to do computing well, we must think of computing not only as a profession, the fundamental question underlying all computing is What can be automated. The term computing is also synonymous with counting and calculating, in earlier times, it was used in reference to the action performed by mechanical computing machines, and before that, to human computers. Computing is intimately tied to the representation of numbers, but long before abstractions like the number arose, there were mathematical concepts to serve the purposes of civilization. These concepts include one-to-one correspondence, comparison to a standard, the earliest known tool for use in computation was the abacus, and it was thought to have been invented in Babylon circa 2400 BC. Its original style of usage was by lines drawn in sand with pebbles, abaci, of a more modern design, are still used as calculation tools today. This was the first known computer and most advanced system of calculation known to date - preceding Greek methods by 2,000 years. The first recorded idea of using electronics for computing was the 1931 paper The Use of Thyratrons for High Speed Automatic Counting of Physical Phenomena by C. E. Wynn-Williams. Claude Shannons 1938 paper A Symbolic Analysis of Relay and Switching Circuits then introduced the idea of using electronics for Boolean algebraic operations, a computer is a machine that manipulates data according to a set of instructions called a computer program. The program has a form that the computer can use directly to execute the instructions. The same program in its source code form, enables a programmer to study. Because the instructions can be carried out in different types of computers, the execution process carries out the instructions in a computer program. Instructions express the computations performed by the computer and they trigger sequences of simple actions on the executing machine. Those actions produce effects according to the semantics of the instructions, computer software or just software, is a collection of computer programs and related data that provides the instructions for telling a computer what to do and how to do it. Software refers to one or more programs and data held in the storage of the computer for some purposes. In other words, software is a set of programs, procedures, algorithms, program software performs the function of the program it implements, either by directly providing instructions to the computer hardware or by serving as input to another piece of software
8.
ASCII
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ASCII, abbreviated from American Standard Code for Information Interchange, is a character encoding standard. ASCII codes represent text in computers, telecommunications equipment, and other devices, most modern character-encoding schemes are based on ASCII, although they support many additional characters. ASCII was developed from telegraph code and its first commercial use was as a seven-bit teleprinter code promoted by Bell data services. Work on the ASCII standard began on October 6,1960, the first edition of the standard was published in 1963, underwent a major revision during 1967, and experienced its most recent update during 1986. Compared to earlier telegraph codes, the proposed Bell code and ASCII were both ordered for more convenient sorting of lists, and added features for other than teleprinters. Originally based on the English alphabet, ASCII encodes 128 specified characters into seven-bit integers as shown by the ASCII chart above. The characters encoded are numbers 0 to 9, lowercase letters a to z, uppercase letters A to Z, basic punctuation symbols, control codes that originated with Teletype machines, for example, lowercase j would become binary 1101010 and decimal 106. ASCII includes definitions for 128 characters,33 are non-printing control characters that affect how text and space are processed and 95 printable characters, of these, the IANA encourages use of the name US-ASCII for Internet uses of ASCII. The ASA became the United States of America Standards Institute and ultimately the American National Standards Institute, there was some debate at the time whether there should be more control characters rather than the lowercase alphabet. The X3.2.4 task group voted its approval for the change to ASCII at its May 1963 meeting, the X3 committee made other changes, including other new characters, renaming some control characters and moving or removing others. ASCII was subsequently updated as USAS X3. 4-1967, then USAS X3. 4-1968, ANSI X3. 4-1977 and they proposed a 9-track standard for magnetic tape, and attempted to deal with some punched card formats. The X3.2 subcommittee designed ASCII based on the earlier teleprinter encoding systems, like other character encodings, ASCII specifies a correspondence between digital bit patterns and character symbols. This allows digital devices to communicate each other and to process, store. Before ASCII was developed, the encodings in use included 26 alphabetic characters,10 numerical digits, ITA2 were in turn based on the 5-bit telegraph code Émile Baudot invented in 1870 and patented in 1874. The committee debated the possibility of a function, which would allow more than 64 codes to be represented by a six-bit code. In a shifted code, some character codes determine choices between options for the character codes. It allows compact encoding, but is reliable for data transmission. The standards committee decided against shifting, and so ASCII required at least a seven-bit code, the committee considered an eight-bit code, since eight bits would allow two four-bit patterns to efficiently encode two digits with binary-coded decimal
9.
Printer (computing)
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In computing, a printer is a peripheral which makes a persistent human-readable representation of graphics or text on paper or similar physical media. The worlds first computer printer was a 19th-century mechanically driven apparatus invented by Charles Babbage for his difference engine, the plotter was used for those requiring high quality line art like blueprints. Laser printers using PostScript mixed text and graphics, like dot-matrix printers, by 1990, most simple printing tasks like fliers and brochures were now created on personal computers and then laser printed, expensive offset printing systems were being dumped as scrap. The HP Deskjet of 1988 offered the same advantages as laser printer in terms of flexibility, inkjet systems rapidly displaced dot matrix and daisy wheel printers from the market. By the 2000s high-quality printers of this sort had fallen under the price point. Even the desire for printed output for offline reading while on mass transit or aircraft has been displaced by e-book readers, today, traditional printers are being used more for special purposes, like printing photographs or artwork, and are no longer a must-have peripheral. Starting around 2010, 3D printing became an area of intense interest and these devices are in their earliest stages of development and have not yet become commonplace. Personal printers are designed to support individual users, and may be connected to only a single computer. These printers are designed for low-volume, short-turnaround print jobs, requiring minimal setup time to produce a copy of a given document. However, they are generally slow devices ranging from 6 to around 25 pages per minute, however, this is offset by the on-demand convenience. Some printers can print documents stored on cards or from digital cameras. Networked or shared printers are designed for high-volume, high-speed printing and they are usually shared by many users on a network and can print at speeds of 45 to around 100 ppm. The Xerox 9700 could achieve 120 ppm, a virtual printer is a piece of computer software whose user interface and API resembles that of a printer driver, but which is not connected with a physical computer printer. It is called a printer by analogy with a printer which produces a two-dimensional document by a similar process of depositing a layer of ink on paper. The choice of print technology has an effect on the cost of the printer and cost of operation, speed, quality and permanence of documents. Some printer technologies dont work with certain types of physical media, cheques can be printed with liquid ink or on special cheque paper with toner anchorage so that alterations may be detected. The machine-readable lower portion of a cheque must be printed using MICR toner or ink, banks and other clearing houses employ automation equipment that relies on the magnetic flux from these specially printed characters to function properly. The following printing technologies are found in modern printers, A laser printer rapidly produces high quality text
10.
System console
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It is a physical device consisting of a keyboard and a screen, and traditionally is a text terminal, but may also be a graphical terminal. System consoles are generalized to computer terminals, which are abstracted respectively by virtual consoles, today communication with system consoles is generally done abstractly, via the standard streams, but there may be system-specific interfaces, for example those used by the system kernel. On traditional minicomputers, the console was a console, an RS-232 serial link to a terminal such as a DEC VT100. This terminal was kept in a secured room since it could be used for certain privileged functions such as halting the system or selecting which media to boot from. Large midrange systems, e. g. those from Sun Microsystems, Hewlett-Packard and IBM, in larger installations, the console ports are attached to multiplexers or network-connected multiport serial servers that let an operator connect a terminal to any of the attached servers. Today, serial consoles are used for accessing headless systems. Also, routers, enterprise network switches and other equipment have RS-232 serial console ports. On PCs and workstations, the computers attached keyboard and monitor have the equivalent function, since the monitor cable carries video signals, it cannot be extended very far. Often, installations with many servers therefore use keyboard/video multiplexers and possibly video amplifiers to centralize console access, in recent years, KVM/IP devices have become available that allow a remote computer to view the video output and send keyboard input via any TCP/IP network and therefore the Internet. Some PC BIOSes, especially in servers, also support serial consoles, even where BIOS support is lacking, some operating systems, e. g. FreeBSD and Linux, can be configured for serial console operation either during bootup, or after startup. It is usually possible to log in from the console, depending on configuration, the operating system may treat a login session from the console as being more trustworthy than a login session from other sources. Command-line interface Console application Console server Linux console Virtual console Win32 console
11.
Cursor (user interface)
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The mouse cursor is also called a pointer, owing to its resemblance in usage to a pointing stick. A cursor is the given to the transparent slide engraved with a hairline that is used for marking a point on a slide rule. The term was transferred to computers through analogy. In text mode displays, it was not possible to show a bar between characters to show where the new text would be inserted, so an underscore or block cursor was used instead. In situations where a block was used, the block was created by inverting the pixels of the character using the boolean math exclusive or function. On text editors and word processors of modern design on bitmapped displays, in a typical text editing application, the cursor can be moved by pressing various keys. These include the four keys, the Page Up and Page Down keys, the Home key, the End key. The position of the cursor also may be changed by moving the pointer to a different location in the document. The blinking of the cursor is usually temporarily suspended when it is being moved, otherwise. In this way, a block cursor may be seen as a piece of selected text one character wide, in some cases, the cursor may split into two parts, each indicating where left-to-right and right-to-left text would be inserted. The I-beam pointer is a cursor shaped like the capital letter I, the purpose of this cursor to indicate text can be highlighted, inserted, or changed. The pointer or mouse cursor echoes movements of the device, commonly a mouse. This kind of cursor is used to manipulate elements of user interfaces such as menus, buttons. It may be called a pointer, because the mouse is the dominant type of pointing device used with desktop computers. The idea of a cursor being used as a marker or insertion point for new data or transformations, such as rotation, blender, for instance, uses a 3D cursor to determine where future operations are to take place. A real-life cursor such as this was featured as a character in the science fiction TV series Automan. Susan Kare, designer of several of the common cursor shapes Creating and controlling browser cursors Cross-browser CSS custom cursors Installing A Cursor On Your Computer
12.
Baudot code
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The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No,2, the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of bits, the symbol rate measurement is known as baud, and is derived from the same name. Technically, five-bit codes began in the 16th century, when Francis Bacon developed the now called Bacons cipher. However, this cipher is not a cipher and as such is not readily suitable for telecommunications. Baudot invented his original code in 1870 and patented it in 1874 and it was a 5-bit code, with equal on and off intervals, which allowed telegraph transmission of the Roman alphabet and punctuation and control signals. It was based on an earlier code developed by Carl Friedrich Gauss and it was a Gray code, nonetheless, the code by itself was not patented because French patent law does not allow concepts to be patented. Baudots original code was adapted to be sent from a manual keyboard, the code was entered on a keyboard which had just five piano type keys, operated with two fingers of the left hand and three fingers of the right hand. Operators had to maintain a rhythm, and the usual speed of operation was 30 words per minute. The table on the shows the allocation of the Baudot code which was employed in the British Post Office for continental. It will be observed that a number of characters in the code are replaced by fractionals in the inland code. Code elements 1,2 and 3 are transmitted by keys 1,2 and 3, code elements 4 and 5 are transmitted by keys 4 and 5, and these are operated by the first two fingers of the left hand. Baudots code became known as International Telegraph Alphabet No,1, and is no longer used. In 1901, Baudots code was modified by Donald Murray, prompted by his development of a typewriter-like keyboard. The Murray system employed an intermediate step, a keyboard perforator, which allowed an operator to punch a tape. At the receiving end of the line, a mechanism would print on a paper tape. For example, the letters are E and T. The ten two-hole letters are AOINSHRDLZ, very similar to the Etaoin shrdlu order used in Linotype machines, ten more letters have three holes, and the four-hole letters are VXKQ
13.
Paragraph
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A paragraph is a self-contained unit of a discourse in writing dealing with a particular point or idea. A paragraph consists of one or more sentences, though not required by the syntax of any language, paragraphs are usually an expected part of formal writing, used to organize longer prose. The oldest classical Greek and Latin writing had little or no space between words and could be written in boustrophedon, over time, text direction became standardized, and word dividers and terminal punctuation became common. The first way to divide sentences into groups was the original paragraphos, the Greek paragraphos evolved into the pilcrow, which in English manuscripts in the Middle Ages can be seen inserted inline between sentences. The hedera leaf has also used in the same way. In ancient manuscripts, another means to divide sentences into paragraphs was a line followed by an initial at the beginning of the next paragraph. An initial is a capital letter, sometimes outdented beyond the margin of the text. This style can be seen, for example, in the original Old English manuscript of Beowulf, outdenting is still used in English typography, though not commonly. Modern English typography usually indicates a new paragraph by indenting the first line and this style can be seen in the United States Constitution from 1787. For additional ornamentation, a leaf or other symbol can be added to the inter-paragraph whitespace. A second common modern English style is to use no indenting, on a typewriter, a double carriage return produces a blank line for this purpose, professional typesetters may put in an arbitrary vertical space by adjusting leading. This style is common in electronic formats, such as on the World Wide Web. Widows and orphans occur when the first line of a paragraph is the last line in a column or page, a recent trendy idea in English is not to indent the first paragraph, but indent those that follow. For example, Robert Bringhurst states that we should Set opening paragraphs flush left, Bringhurst explains as follows, The function of a paragraph is to mark a pause, setting the paragraph apart from what precedes it. If a paragraph is preceded by a title or subhead, the indent is superfluous, the Elements of Typographic Style states that at least one en should be used to indent paragraphs after the first, noting that that is the practical minimum. An em space is the most commonly used paragraph indent, miles Tinker, in his book Legibility of Print, concluded that indenting the first line of paragraphs increases readability by 7%, on the average. In word processing and desktop publishing, a return or paragraph break indicates a new paragraph. This distinction allows word wrap to automatically re-flow text as it is edited, the software may apply vertical whitespace or indenting at paragraph breaks, depending on the selected style
14.
HTML
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Hypertext Markup Language is the standard markup language for creating web pages and web applications. With Cascading Style Sheets and JavaScript it forms a triad of cornerstone technologies for the World Wide Web, Web browsers receive HTML documents from a webserver or from local storage and render them into multimedia web pages. HTML describes the structure of a web page semantically and originally included cues for the appearance of the document, HTML elements are the building blocks of HTML pages. With HTML constructs, images and other objects, such as interactive forms and it provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists, links, quotes and other items. HTML elements are delineated by tags, written using angle brackets, tags such as <img /> and <input /> introduce content into the page directly. Include explicit close tags for elements that permit content but are left empty, by carefully following the W3Cs compatibility guidelines, a user agent should be able to interpret the document equally as HTML or XHTML. For documents that are XHTML1.0 and have made compatible in this way. When delivered as XHTML, browsers should use an XML parser, HTML4 defined three different versions of the language, Strict, Transitional and Frameset. The Transitional and Frameset versions allow for presentational markup, which is omitted in the Strict version, instead, cascading style sheets are encouraged to improve the presentation of HTML documents. Because XHTML1 only defines an XML syntax for the language defined by HTML4, as this list demonstrates, the loose versions of the specification are maintained for legacy support. However, contrary to popular misconceptions, the move to XHTML does not imply a removal of this legacy support, rather the X in XML stands for extensible and the W3C is modularizing the entire specification and opening it up to independent extensions. The primary achievement in the move from XHTML1.0 to XHTML1.1 is the modularization of the entire specification, the strict version of HTML is deployed in XHTML1.1 through a set of modular extensions to the base XHTML1.1 specification. Likewise, someone looking for the loose or frameset specifications will find similar extended XHTML1.1 support, the modularization also allows for separate features to develop on their own timetable. So for example, XHTML1.1 will allow quicker migration to emerging XML standards such as MathML, in summary, the HTML4 specification primarily reined in all the various HTML implementations into a single clearly written specification based on SGML. XHTML1.0, ported this specification, as is, next, XHTML1.1 takes advantage of the extensible nature of XML and modularizes the whole specification. XHTML2.0 was intended to be the first step in adding new features to the specification in a standards-body-based approach. The WHATWG considers their work as living standard HTML for what constitutes the state of the art in major browser implementations by Apple, Google, Mozilla, Opera, hTML5 is specified by the HTML Working Group of the W3C following the W3C process. HTML lacks some of the found in earlier hypertext systems, such as source tracking, fat links
15.
Whitespace character
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In computer programming, white space is any character or series of characters that represent horizontal or vertical space in typography. When rendered, a character does not correspond to a visible mark. For example, the common whitespace symbol U+0020 SPACE, also ASCII32, represents a blank space punctuation character in text, with many keyboard layouts, a horizontal whitespace character may be entered through the use of a spacebar. Horizontal white space may also be entered on many keyboards through the use of the Tab ↹ key, although the length of the space may vary. Vertical white space is a bit more varied as to how it is encoded, many early computer games used such codes to draw a screen. The term white space is based on the appearance on ordinary paper. However they are coded inside an application, white space can be processed the same as any character code. The most common whitespace characters may be typed via the bar or the tab key. Depending on context, a line-break generated by the return or enter key may be considered space as well. The table below lists the twenty-five characters defined as characters in the Unicode Character Database. Seventeen use a definition of white space consistent with the algorithm for writing and are known as Bidi-WS characters. The remaining characters may also be used, but are not of this Bidi type, note, Depending on the browser and fonts used to view the following table, not all spaces may be displayed properly. Some fonts display the character as a blank, however the Unicode standard explicitly states that it does not act as a space. Exact space The Cambridge Z88 provided a special exact space displayed as … by the systems display driver. It was therefore known as dot space in conjunction with BBC BASIC. Under codepoint 224 the computer provided a special three-character-cells-wide SPACE symbol SPC. In some cases, spaces are shown simply as blank space, many different characters could be used to produce spaces, and non-character functions can also affect white space. In computer character encodings, there is a normal general-purpose space whose width will vary according to the design of the typeface, typical values range from 1/5 em to 1/3 em
16.
Hexadecimal
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In mathematics and computing, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, Hexadecimal numerals are widely used by computer system designers and programmers. As each hexadecimal digit represents four binary digits, it allows a more human-friendly representation of binary-coded values, one hexadecimal digit represents a nibble, which is half of an octet or byte. For example, a byte can have values ranging from 00000000 to 11111111 in binary form. In a non-programming context, a subscript is typically used to give the radix, several notations are used to support hexadecimal representation of constants in programming languages, usually involving a prefix or suffix. The prefix 0x is used in C and related languages, where this value might be denoted as 0x2AF3, in contexts where the base is not clear, hexadecimal numbers can be ambiguous and confused with numbers expressed in other bases. There are several conventions for expressing values unambiguously, a numerical subscript can give the base explicitly,15910 is decimal 159,15916 is hexadecimal 159, which is equal to 34510. Some authors prefer a text subscript, such as 159decimal and 159hex, or 159d and 159h. example. com/name%20with%20spaces where %20 is the space character, thus ’, represents the right single quotation mark, Unicode code point number 2019 in hex,8217. In the Unicode standard, a value is represented with U+ followed by the hex value. Color references in HTML, CSS and X Window can be expressed with six hexadecimal digits prefixed with #, white, CSS allows 3-hexdigit abbreviations with one hexdigit per component, #FA3 abbreviates #FFAA33. *nix shells, AT&T assembly language and likewise the C programming language, to output an integer as hexadecimal with the printf function family, the format conversion code %X or %x is used. In Intel-derived assembly languages and Modula-2, hexadecimal is denoted with a suffixed H or h, some assembly languages use the notation HABCD. Ada and VHDL enclose hexadecimal numerals in based numeric quotes, 16#5A3#, for bit vector constants VHDL uses the notation x5A3. Verilog represents hexadecimal constants in the form 8hFF, where 8 is the number of bits in the value, the Smalltalk language uses the prefix 16r, 16r5A3 PostScript and the Bourne shell and its derivatives denote hex with prefix 16#, 16#5A3. For PostScript, binary data can be expressed as unprefixed consecutive hexadecimal pairs, in early systems when a Macintosh crashed, one or two lines of hexadecimal code would be displayed under the Sad Mac to tell the user what went wrong. Common Lisp uses the prefixes #x and #16r, setting the variables *read-base* and *print-base* to 16 can also used to switch the reader and printer of a Common Lisp system to Hexadecimal number representation for reading and printing numbers. Thus Hexadecimal numbers can be represented without the #x or #16r prefix code, MSX BASIC, QuickBASIC, FreeBASIC and Visual Basic prefix hexadecimal numbers with &H, &H5A3 BBC BASIC and Locomotive BASIC use & for hex. TI-89 and 92 series uses a 0h prefix, 0h5A3 ALGOL68 uses the prefix 16r to denote hexadecimal numbers, binary, quaternary and octal numbers can be specified similarly
17.
C (programming language)
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C was originally developed by Dennis Ritchie between 1969 and 1973 at Bell Labs, and used to re-implement the Unix operating system. C has been standardized by the American National Standards Institute since 1989, C is an imperative procedural language. Therefore, C was useful for applications that had formerly been coded in assembly language. Despite its low-level capabilities, the language was designed to encourage cross-platform programming, a standards-compliant and portably written C program can be compiled for a very wide variety of computer platforms and operating systems with few changes to its source code. The language has become available on a wide range of platforms. In C, all code is contained within subroutines, which are called functions. Function parameters are passed by value. Pass-by-reference is simulated in C by explicitly passing pointer values, C program source text is free-format, using the semicolon as a statement terminator and curly braces for grouping blocks of statements. The C language also exhibits the characteristics, There is a small, fixed number of keywords, including a full set of flow of control primitives, for, if/else, while, switch. User-defined names are not distinguished from keywords by any kind of sigil, There are a large number of arithmetical and logical operators, such as +, +=, ++, &, ~, etc. More than one assignment may be performed in a single statement, function return values can be ignored when not needed. Typing is static, but weakly enforced, all data has a type, C has no define keyword, instead, a statement beginning with the name of a type is taken as a declaration. There is no function keyword, instead, a function is indicated by the parentheses of an argument list, user-defined and compound types are possible. Heterogeneous aggregate data types allow related data elements to be accessed and assigned as a unit, array indexing is a secondary notation, defined in terms of pointer arithmetic. Unlike structs, arrays are not first-class objects, they cannot be assigned or compared using single built-in operators, There is no array keyword, in use or definition, instead, square brackets indicate arrays syntactically, for example month. Enumerated types are possible with the enum keyword and they are not tagged, and are freely interconvertible with integers. Strings are not a data type, but are conventionally implemented as null-terminated arrays of characters. Low-level access to memory is possible by converting machine addresses to typed pointers
18.
Enter key
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On computer keyboards, the enter key in most cases causes a command line, window form, or dialog box to operate its default function. This is typically to finish an entry and begin the desired process and it normally has an arrow pointing down and left, which is the symbol for carriage return. In contrast, the Enter key is commonly labelled with its name in plain text on generic PC keyboards, the return/enter key can have various physical shapes. On some keyboard layouts, the return and enter key are two different keys, an artifact of the handling of newlines by different operating systems. As an example, on the Macintosh, the key is the usual key. While using the tool in Adobe Photoshop, the return key produces a new line while the enter key ends editing mode. On IBMs 3270 and 5250 line of terminals, the Enter key was located to the right of the bar and was used to send the contents of the terminals buffer to the host computer. The Return key was located in a standard location and was used to generate a new line. In technical terms, the Macintosh keyboard maps the return key to a carriage return, historically, many computer models did not have a separate keypad, and only had one button to function as Enter or Return. For example, the Commodore 64 had only the Return key, in Mathematica, the Return key creates a new line, whereas the Enter key submits the current command for execution. In pocket calculator-like programs, the key of the numeric keypad acts like the equal to button to obtain the result of the previously entered operations. In graphical computer applications, the enter or return key is used to close. In modern word processing applications, pressing the return key ends a paragraph, spacing between the paragraphs can be defined through paragraph styles. Before computers, on electric typewriters the “Return” key was kept comparatively large and this is due to the frequency of usage, and therefore, is kept large to reduce the likelihood of finger slips
19.
Computer keyboard
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In computing, a computer keyboard is a typewriter-style device which uses an arrangement of buttons or keys to act as a mechanical lever or electronic switch. Following the decline of punch cards and paper tape, interaction via teleprinter-style keyboards became the input device for computers. A keyboard typically has characters engraved or printed on the keys, however, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or signs, other keys or simultaneous key presses can produce actions or execute computer commands. In normal usage, the keyboard is used as a text entry interface to type text and numbers into a word processor, in a modern computer, the interpretation of key presses is generally left to the software. A computer keyboard distinguishes each physical key from every other and reports all key presses to the controlling software, Keyboards are also used for computer gaming, either with regular keyboards or by using keyboards with special gaming features, which can expedite frequently used keystroke combinations. A keyboard is used to give commands to the operating system of a computer, such as Windows Control-Alt-Delete combination. A command-line interface is a type of user interface operated entirely through a keyboard and it was through such devices that modern computer keyboards inherited their layouts. Earlier models were developed separately by individuals such as Royal Earl House, earlier, Herman Hollerith developed the first keypunch devices, which soon evolved to include keys for text and number entry akin to normal typewriters by the 1930s. From the 1940s until the late 1960s, typewriters were the means of data entry. The keyboard remained the primary, most integrated computer peripheral well into the era of personal computing until the introduction of the mouse as a device in 1984. By this time, text-only user interfaces with sparse graphics gave way to comparatively graphics-rich icons on screen, One factor determining the size of a keyboard is the presence of duplicate keys, such as a separate numeric keyboard, for convenience. A keyboard with few keys is called a keypad, another factor determining the size of a keyboard is the size and spacing of the keys. Reduction is limited by the consideration that the keys must be large enough to be easily pressed by fingers. Alternatively a tool is used for pressing small keys, standard alphanumeric keyboards have keys that are on three-quarter inch centers, and have a key travel of at least 0.150 inches. Desktop computer keyboards, such as the 101-key US traditional keyboards or the 104-key Windows keyboards, include characters, punctuation symbols, numbers. The internationally common 102/104 key keyboards have a left shift key. Also the enter key is usually shaped differently, computer keyboards are similar to electric-typewriter keyboards but contain additional keys, such as the command or Windows keys
20.
Compose key
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A compose key, also called multi key, is a part of the computer keyboard that is—or behaves like—a kind of special dead key. Thus, unlike a modifier key, which must be held down, the effect of the compose key is to convert to a dead key every specified key that is pressed after it. The next keypress triggers the insertion of a character, typically a precomposed character or a symbol. Being a dead key, the key only needs one key position. This is ideally in the Base shift state, while the key positions may be attributed to other characters or dead keys. On the other hand, with respect to compact keyboards, the key may also be hidden in one of the present classic dead keys. More generally, any dead key may be programmed to compose more than what it is expected to produce. Having one dedicated compose key on keyboard, regardless of the number of other dead keys. For ergonomics, the place for the Compose key is Right Alt. If they do, the user might prefer to have Compose on Left Alt. Alternately, the Compose key may be placed on Right Ctrl, as actual keyboards can manage key rollover, the compose key does not really have to be released before the subsequent keystrokes. This makes it possible for experienced typists to enter composed characters rapidly, the typing speed is increased if the compose key can be acted with one thumb while other fingers are already about to hit the keys of the sequence. At the beginning, the Compose sequences followed handwriting and the overstrike technique, for example, striking Compose, followed by n, and then ~, produced the character ñ. This order is still in use, but multidiacriticized characters are hard to obtain this way, the inverse order is known from standard dead keys as present on the last typewriters and as used today on computer keyboards, Compose~n for ñ. Likewise, striking Compose, followed by O, and then C and this allows typing Compose^a, for ấ. There is no limit on combinations or sequence length, which only should respect the rules of mnemonics and ergonomics. For example, U+278C ➌ DINGBAT NEGATIVE CIRCLED SANS-SERIF DIGIT THREE might be inserted when the sequence is typed. This example is based on the use of @ for all circled characters, % after @ for all negative circled, the choice of % for negative can be made with respect to ergonomics on a U. S
21.
Control key
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The Control key is located on or near the bottom left side of most keyboards, with many featuring an additional one at the bottom right. It is usually labeled Ctrl on keyboards which use English abbreviations for key labeling, abbreviations in the language of the keyboard layout also are in use. E. g. the German layout uses Strg as required by the German standard DIN2137, also, there is a standardized keyboard symbol, given in ISO/IEC 9995-7 as symbol 26, and in ISO7000 “Graphical symbols for use on equipment” as symbol ISO-7000-2028. This symbol is encoded in Unicode as U+2388 helm symbol, on teletypewriters and early keyboards, holding down the Control key while pressing another key zeroed the leftmost two bits of the seven bits in the generated ASCII character. This allowed the operator to produce the first 32 characters in the ASCII table, aptly, these characters are also called control characters. In modern computers, the interpretation of keypresses is generally left to the software, modern keyboards distinguish each physical key from every other and report all keypresses and releases to the controlling software. This additional flexibility is not often taken advantage of and it usually does not matter, for example, when the original purpose of the ASCII control characters became either obsolete or seldom used, later software appropriated the Control key combinations for other purposes. The traditional layout was preserved for later workstation systems and is associated with Unix workstations. Keyboards from Sun Microsystems came in two layouts, Unix and PC-style, with the Unix layout having the traditional placing of the Control key, the keyboards produced for One Laptop Per Child computers also have the Control key in this location. Other vendors produce keyboards for different computer systems with this placement of the Control key, Keyboard layout preferences specifically to address this need are available in some operating systems. Others leave the key in the lower-left corner of the keyboard. The choice of location for the key often comes down to the typists hand shape. There are several notations for pressing the Control key in conjunction with another key. Generally, the Command key, labeled with the ⌘ symbol on Apple Macintosh computers, macintoshes also have a Control key, but it has different functionality. The original Apple mouse design reduced complexity by only offering one button, as the interface developed, Contextual Menus were offered to access extra options. Another button was needed to access these, on Unix and Windows, the user had other mouse buttons to use. On Classic Mac OS and macOS, the Control key is used to invoke a right-click, Apple calls this a secondary click as left-handers can choose which side this button is on. It is mostly used as a key for key-combinations
22.
Shift key
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The shift key is a modifier key on a keyboard, used to type capital letters and other alternate upper characters. There are typically two shift keys, on the left and right sides of the row below the home row,2 Type-Writer of 1878, the No.1 model was capital-only. On the US layout and similar layouts, characters that typically require the use of the shift key include the parentheses, the question mark, the exclamation point. When the caps lock key is engaged, the key can be used to type lowercase letters on many operating systems. The keyboard symbol for the Shift key is given in ISO/IEC 9995-7 as symbol 1, in Unicode 6.1, the character approximating this symbol best is U+21E7 upwards white arrow. This symbol is used to denote the Shift key on modern keyboards. This symbol also is used in texts to denote the shift key, on computer keyboards, as opposed to typewriter keyboards, the shift key can have many more uses, It is sometimes used to modify the function keys. Modern Microsoft Windows keyboards typically have only 12 function keys, Shift+F1 must be used to type F13, Shift+F2 for F14 and it can modify various control and alt keys. For example, if Alt-Tab is used to cycle through open windows, holding shift while in a word processor will anchor the insertion point, such that moving the pointer and clicking the mouse to a new point will select the range of text in between. The shift key can also be used to modify the behavior on a computer. For example, holding shift while clicking on a link in a web browser might cause the page to open in a new window, in some web browsers, holding shift while scrolling will scan through previously viewed web pages. In macOS, holding shift while performing actions, such as minimising a window or enabling/disabling Dashboard or Mission Control. For some animations, holding control will make the move just slightly slower. On some keyboards, if both shift keys are held down only some letters can be typed. For example, on the Dell keyboard Model RT7D20 only 16 letters can be typed and this phenomenon is known as masking and is a fundamental limitation of the way the keyboard electronics are designed. The following is a list of actions involving the shift key for the Microsoft Windows operating system, altGr key Command key Option key StickyKeys
23.
Alt key
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For a list of keyboard shortcuts, see Table of keyboard shortcuts ⌥ Opt or Alt The Alt key on a computer keyboard is used to change the function of other pressed keys. Thus, the Alt key is a key, used in a similar fashion to the Shift key. For example, simply pressing A will type the letter a, but if you hold down either Alt key while pressing A, the computer will perform an Alt+A function, the international standard ISO/IEC 9995-2 calls it Alternate key. The key is located on side of the Space bar. Both placements are in accordance with ISO/IEC 9995-2, the standardized keyboard symbol for the Alt key is given in ISO/IEC 9995-7 as symbol 25, and in ISO7000 “Graphical symbols for use on equipment” as symbol ISO-7000-2105. This symbol is encoded in Unicode as U+2387 alternative key symbol, the Alt key should not be confused with the Altmode key on some Teletype and ASCII terminals, which is a synonym for the ASCII escape character. The Alt key has come to replace the Meta key of the old MIT keyboards, in their original function, both Alt and Meta would set the high bit of the signal generated by the key to 1. However, in software, due to the requirement of the high bit for internationalization. Since the 1990s Alt has been printed on the Option key on most Mac keyboards, Alt is used in non-Mac software, such as non-macOS Unix and Windows programs, but in macOS it is always referred as the Option key. The Option keys behaviour in macOS differs slightly from that of the Windows Alt key, the Alt key is well known as part of the key combinations, Ctrl+Alt+Delete brings up a task manager in some operating systems, see Control-Alt-Delete. Alt+⌘ Cmd+Esc brings up the Force Quit window in Apple’s macOS, ctrl+Alt+← Backspace usually causes the X display server to shut down or to restart, see Control-Alt-Backspace. Alt+F4 closes the current window on most windowing systems, alt+Tab ↹ switches between the currently opened windows on most windowing systems, see Alt-Tab. Alt+↵ Enter allows for a new line when Enter does another command, in Microsoft Windows, holding down the Alt key while typing in numbers on the numeric keypad allows the user to type special characters not normally available on the keyboard. For example, holding down Alt while typing 0225 on the numeric keypad will result in á and these extended keyboard characters are useful for persons using foreign languages, mathematics, currency symbols, business use, etc. Some computers work the same if the Num Lock key is on, on a Macintosh, the Alt key is called the Option key. It is not used to enter numeric character codes, instead, keyboard letters and numbers are used. The diagram below shows the characters a US Mac keyboard will produce when the Option key is pressed. The highlighted orange keys show the accents available from the combination of the Alt key, the accent then can be applied to associated letters both lower and uppercase
24.
Option key
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The Option key is a modifier key present on Apple keyboards. It is located between the Control key and Command key on a typical Mac keyboard, there are two option keys on modern Mac desktop and notebook keyboards, one on each side of the space bar. Apple commonly uses the symbol U+2325 ⌥ option key to represent the Option key, from 1980 to 1984, on the Apple II family, this key was known as the closed apple key, and had a black line drawing of a filled-in apple on it. Since the 1990s, alt typically appears on the key, as well, for use as an Alt key with non-Mac software, such as Unix, however, the Option key in a Mac operating system functions differently from the Alt key under other Unix-like systems or Microsoft Windows. Most notably, it is not used to access menus or hotkeys, but is used as a modifier for other command codes. In this regard, it is akin to the AltGr key, the options available differ depending on the keyboard input locale that the user has selected. English keyboard input, ⌥ Option+a produces the å character, and ⌥ Option+4 produces the cent sign ¢, the Option key can also provide access to dead key functionality. For example, holding down ⌥ Option while pressing will create a highlighted grave accent which will be added to the letter if possible – so if an e is then pressed. If an r is pressed instead, the two characters are not compatible so the result is r, the highlighted orange keys show the accents available from the combination of the ⌥ Option key and the keyboard characters e i n u. The accent then can be applied to associated letters both lower and uppercase, the additional characters a Mac will produce are a combination of both the ⌥ Option key and the ⇧ Shift key pressed down together. With this combination pressed the keyboard will now produce a different set or a version of the previous set in some cases. The Option key is used in conjunction with special keys like Tab ↹, delete. For example, ⌥ Option+Return typically produces a break that is not interpreted as a paragraph break. The key is used to provide for alternative menu items. Examples, Safari, Finder - the Option key causes the Close Window menu item to switch to Close All Windows when pressed down, consequently, clicking a windows close box with the option key depressed invokes close all as well. This functionality is a de facto Macintosh standard and available in other programs. IPhoto - the rotate image button toggles between a right and a rotate left. The iPhoto example is an example of a control whose behavior is governed by a preference which is inverted by holding down the Option key
25.
Apple Keyboard
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The Apple Keyboard is a keyboard designed by Apple Inc. first for the Apple line, then the Macintosh line of computers. Dozens of models have been released over time, including the Apple Extended Keyboard, there are currently two keyboards offered by Apple, a full-sized version using USB, and the Apple Magic Keyboard, which connects via Bluetooth and omits the numeric keypad of the full-sized model. Both share a look and feel, based on a very thin aluminum chassis and laptop-style low-profile keys. To serve the functionality of the Macintosh operating systems, the Apple Keyboards layout differs somewhat from that of the ubiquitous IBM PC keyboard, mainly in its modifier, some of these keys have unique symbols defined in the Unicode block Miscellaneous Technical. Features different from other keyboards include, The Command key, used in most Mac keyboard shortcuts, compared to their equivalents on the standard IBM PC keyboard layout the Command key and the Option key are located in reverse order. The open and separate closed Apple logo keys on the Apple II series, the open-Apple key was combined with the Command key on Apple Desktop Bus keyboards where it remained after the Apple II line was discontinued. The Option key, for entering diacritics and other special characters, like the Shift and Control keys, the Option key serves as a modifier for the Command key shortcuts, as well as being used to type many special characters. It serves the function of the key in Apple II applications. It functions as the Alt key in Unix and Windows environments, compared to their equivalents on the standard IBM PC keyboard layout the Command key and the Option key are located in reverse order. Full-sized desktop keyboards with a dedicated numpad have function keys that can range up to F15, F16, f17-F19 keys were introduced with the aluminium USB keyboard. Compact keyboards such as the bluetooth wireless aluminium keyboard and the keyboards on all Intel-based Macintosh notebooks range from F1-F12 only. A Clear key, instead of a Num Lock key, on models with full numeric keypads, as these are dedicated to numeric input, in Unicode, the Clear key is represented by U+2327 ⌧ X IN A RECTANGLE BOX, defined as clear key. An equals key added to the numeric keypad, a Help key, instead of an Insert key, or on the most recent aluminum keyboards, a fn key, which toggles the function of the function keys between their default functions and special functions. Notebook computers typically include additional assignments shared with function keys – reduce and increase brightness, volume up, volume down, mute, and eject. Apple, since the release of the Pro Keyboard, provides these last four keys on desktop keyboards above the numeric keypad where status indicator lights are on many IBM PC keyboards. On the newest aluminum keyboard, these functions are accessed with the function keys, on Apple Desktop Bus keyboards, a power key, used to turn on computers that supported it. Most of its functions were transferred to the key in such later keyboards. The Apple UK keyboard layout has the @ and keys in their US locations and these are normally reversed on non-Apple UK keyboards
26.
AltGr key
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AltGr is a modifier key found on some computer keyboards and is primarily used to type characters that are unusual for the locale of the keyboard layout, such as currency symbols and accented letters. On a typical, IBM-compatible PC keyboard, the AltGr key, in macOS, the Option key has functions similar to the AltGr key. AltGr is used similarly to the Shift key, it is held down when another key is struck in order to obtain a character other than the one that the latter normally produces, AltGr and Shift can also sometimes be combined to obtain yet another character. However, IBM states that AltGr is an abbreviation for alternate graphic, AltGr was originally introduced as a means to produce box-drawing characters, also known as pseudographics, in text user interfaces. These characters are, however, much less useful in graphical user interfaces, originally, US PC keyboards did not have an AltGr key because that was relevant to only non-US markets, they simply had left and right Alt keys. The right Alt key is usually an equivalent of the AltGr key because both the right Alt key and the AltGr key share the same scancode and are indistinguishable by software. However, on some keyboards it may not be the case, on compact keyboards like those of netbooks, the right Alt key may be missing altogether. For comparison, the US-International keyboard layout follows, note that the /~ key has been omitted, it doesnt produce any characters together with the AltGr key with or without Shift. It generally produces a \, although, applications receive a different keycode and can instead use the key to, for example. In UK & Ireland keyboard layouts, the two symbols printed on most keyboards which require the AltGr key are, € the Euro currency symbol. Either |, the bar or ¦, the broken vertical bar. Located on the /¬ key, to the left of 1. The other bar symbol is the symbol on the \ key immediately to the left of the Z key. The two latter symbols interchange places in UK keyboards according to the system in use. Using the AltGr key on Linux produces many foreign characters and international symbols, details are to be found at QWERTY § United Kingdom Layout. On South Slavic Latin keyboards, the letters and special characters are created using AltGr, On Belgian keyboards. Those shown in bold are printed on the keys, and common to all systems, ° ª º ₢ ° Some notes, The AltGr+C combination results in the symbol ₢ for the former Brazilian currency, the Brazilian cruzeiro. The AltGr+Q, AltGr+W, AltGr+E combinations are useful as a replacement for the /. key, which is physically absent on non-Brazilian keyboards
27.
Command key
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The Command key, also historically known as the Apple key, clover key, open-Apple key, splat key, pretzel key, or propeller key, is a modifier key present on Apple keyboards. The Command keys purpose is to allow the user to enter commands in applications. An extended Macintosh keyboard — the most common type — has two keys, one on each side of the space bar, some compact keyboards have one only on the left. The ⌘ symbol was chosen by Susan Kare after Steve Jobs decided that the use of the Apple logo in the system would be an over-use of the logo. Apples adaptation of the symbol — encoded in Unicode at U+2318 ⌘ — was derived in part from its use in Scandinavian countries to denote places of interest, the symbol is known by various other names, including Saint Johns Arms and Bowen knot. Apples computers up through the 1979 Apple II Plus did not have a command key. The first model on which it appeared was the 1980 Apple III and this allowed for flexible combinations of a modifier key and base key with just a few extra wires and no ROM changes, since the Apple II could only register one key press at a time. In all these cases, the left Apple key had an outlined open Apple logo, the Apple Lisa had only the closed Apple logo. Thus, the ⌘ symbol appears in the Macintosh menus as the primary modifier key symbol, the original Macintosh also had an Option key which was used primarily for entering extended characters. In 1986, the Apple IIGS was introduced, like the newer Macintosh computers to come, such as the Macintosh SE, it used the Apple Desktop Bus for its keyboard and mouse. However, it was still an Apple II, the Apple symbol was removed in the keyboards 2007 redesign, making room for the keys name to appear. In the US, the keyboard now uses the command, in Europe. On the keyboard of the NeXT Computer that key was marked Command in green, the menus were not marked with a symbol denoting the command key. Besides being used as a key for keyboard shortcuts it was also used to alter the function of some keys. Command+⇧ Shift toggles alpha lock, Command+Return sends Enter and Command+Volume-down toggles Mute, the functions were printed in green on the front side of the modified keys. This was also done on the Z, X, C and V keys Command-Alternate-* triggers a non catchable hardware reset thereby hard rebooting the computer, the Macintosh Human Interface Guidelines have always recommended that developers use the Command key for this purpose. A small set of commands are standard across nearly all applications. If an application needs more shortcuts than can be obtained with the letters of the Latin alphabet
28.
Windows key
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The Windows logo key is a keyboard key which was originally introduced on the Microsoft Natural keyboard in 1994. This key became a key on PC keyboards. Tapping this key invokes the operating systems start menu, if it has one, in Windows, Ctrl+Esc performs the same function, in case the keyboard lacks this key. In laptop and other compact keyboards it is common to have just one Windows key, also, on Microsofts Entertainment Desktop sets, the Windows key is in the middle of the keyboard, below all other keys. This requirement was relaxed in Windows 8.1, allowing the Windows key to be placed on any bezel or edge of the unit, Microsoft regulates the appearance of the Windows key logo picture with a specially crafted license for keyboard manufacturers. In Common Building Block Keyboard Specification, all CBB compliant keyboards were to comply with the Windows Vista Hardware Start Button specification beginning in 2007-06-01. On Windows 9x and Windows NT families of Windows operating system, tapping the Windows key by itself traditionally revealed Windows Taskbar, in Windows Server 2012 and Windows 8, this key launches the Start menu but doesnt show the taskbar. However, this feature was added back into Windows 10, pressing the key in combination with other keys allows invoking many common functions through the keyboard. Holding down Ctrl+Esc will not substitute for the Windows key in these combinations, below is a list of notable shortcuts. Unless otherwise noted, they are valid in the version of Windows. The following shortcuts are valid in Windows 95 and Windows NT4.0, ⊞ Win Opens the Start Menu ⊞ Win+D shows the desktop, or restore hidden programs when pressed a second time. ⊞ Win+E opens Windows Explorer with folder pane on left side of window, ⊞ Win+F opens Find files and folders. ⊞ Win+⇧ Shift+M restores windows that were minimized with ⊞ Win+M, ⊞ Win+R opens the Run dialog box. ⊞ Win+Pause or ⊞ Win+Break opens properties of My Computer, ⊞ Win+Tab ↹ cycles through taskbar buttons. Windows XP adds the following shortcuts, ⊞ Win+B selects the first icon in the Notification Area. ⊞ Win+Ctrl+F opens Search for Computers, ⊞ Win+Ctrl+Alt+↵ Enter toggles full screen in Internet Explorer. This shortcut has been discontinued, replaced by F11, ⊞ Win+L locks the desktop and prepares for switching users if Fast User Switching is enabled. Windows XP Media Center Edition adds the following, ⊞ Win+Alt+↵ Enter starts Windows Media Center, Windows Vista adds the following shortcuts, ⊞ Win+Space bar brings the Windows Sidebar to the front
29.
IntelliType
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Microsoft IntelliType is the brand driver for Microsofts series of computer keyboards. Microsoft releases versions for both Windows and Mac OS X and it has been succeeded by Microsoft Mouse and Keyboard Center, which combines IntelliType with IntelliPoint. IntelliType supports all known Microsoft keyboards, however, advanced features may only be available on certain models. Note, Version 8.0 and above dropped PS/2 support for the following list, as even adapters cant assist, Microsoft keeps version 7.1 as an offered download for users who still own keyboards with PS/2 connectors. If the keyboard has multimedia buttons, the user can define them to run any program or action, on-screen indication of NumLock/CapsLock toggling with some keyboards. On-screen indication of volume level when level is changed, while the user could always define special keys, it was only possible since version 6.3 to define them not just globally but also per application. Version 6.2 forced the user to check for updates by installing and launching the file dpupdchk. exe in the background. It must stay in the background for the control panels settings to launch, Version 6.3 fixed this behavior by only making it an opt-in option during the installation. Some workaround exists, This behavior continues to be an issue as of Version 8, Microsoft Mouse and Keyboard Center IntelliPoint — Microsoft mouse driver
30.
Space-cadet keyboard
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It was inspired by the Knight keyboard, which was developed for the Knight TV system, used with MITs Incompatible Timesharing System. The Symbolics-labeled version shown here was used with the LM-2. The space-cadet keyboard was equipped with seven modifier keys, four keys for bucky bits, meta had been introduced on the earlier Knight keyboard, while Hyper and Super were introduced by this keyboard. Many keys had three symbols on them, accessible via the keys, a letter and a symbol on the top. For example, the L key had an L and an arrow on the top. On this keyboard, it is possible to type over 8,000 different characters and this allowed the user to type very complicated mathematical text, and also to have thousands of single-character commands at their disposal. Many users were willing to memorise the command meanings of many characters if it reduced typing time. This attitude shaped the interface of Emacs, compare the use of the Esc key in vi, due to the convenient position of the key on the ADM-3A terminal. Other users, however, thought that so many bucky bits was overkill and this keyboard included a Macro key which had limited application support. It also included four Roman Numeral keys which allowed for interaction with lists of four or fewer choices. Space-cadet Keyboard and Lisp Machine Keyboards
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Fn key
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The Fn key, short form for function, is a modifier key on many keyboards, especially on laptops, used in a compact layout to combine keys which are usually kept separate. It is typically found on laptops due to their keyboard size restrictions and it is also found on many full-sized multimedia keyboards as the F-Lock key. It is mainly for the purpose of changing display or audio settings quickly, such as brightness, contrast, or volume, and is held down in conjunction with the appropriate key to change the settings. Typically, in a compact layout the area of the keyboard is kept in much the same layout as with a full-sized keyboard. This allows typists to enter text without having to learn a new layout, the symbol that is accessed through pressing Fn is often printed on the key in a smaller font, a box, or different color. This 78-key UK layout is taken from the Apple iBook, the Fn key is a form of meta-modifier key, in that it causes the operating system to see altered scancodes when other keys on the keyboard are pressed. This allows the keyboard to directly emulate a keyboard, so the operating system can use standard keymaps designed for a full-sized keyboard. However, because the system has no notion of the Fn key. There is not yet a standard for the placement of the Fn key. This usually means that the Control key is reduced in size, conversely, Lenovo currently arrange keyboards on their ThinkPad computers with the Fn key as the lowest-left, making Control the second-from-left on the bottom row. This arrangement is unique to ThinkPads amongst all laptops shipped with Windows. Lenovo, however, have since circa 2011 allowed users to reverse the Fn, a different solution, which side-steps the Fn key placement issue altogether, is to remap the Caps-Lock key as Control. Paramount seems to be whether the user keeps their palm stationary on a wrist rest or not, other factors include the control keys size, displacement, and position relative to the left-shift key. A touch typist who prefers to keep their palm resting on a position has difficulty reaching a lower-left control. Executing a control-and-shift operation with a right-displaced-control involves curling the little finger slightly underneath the ring-finger, Control key combinations involving the upper-left of the keyboard, including the keys require either moving the hand, or using the right-control key with the opposite hand. A user who hovers their hands and/or moves them laterally may prefer the lower-left control, as combined with movement of the palm and it also allows control-and-shift operations to be performed without curling the little finger underneath. Some workarounds include using little-finger-shift and ring-finger-control or thumb-control presses, such change to the point of origin does reduce the useful radius of the first four fingers across the keyboard, yet may be more ergonomic for the hand. On a fullsize keyboard, some users access the lower-left Control key using the side of their palm, a technique which is not generally possible on shallow throw laptop keyboards with wrist rests
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Lock key
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LOCK is a function that locks part of a keyboard keys into a distinct mode of operation, depending on the lock settings selected. Most keyboards have three different types of functions, Number Lock – Num Lock. Allows the user to type numbers by pressing the keys on the pad, rather than having them act as up, down, left, right, page up, end. Usually located in the left corner of the number pad. When enabled, letters the user types will be in uppercase by default rather than lowercase, located at left end of the keyboard, above the left shift key. In some applications, such as spreadsheets, the mode is used to change the behavior of the cursor keys to scroll the document instead of the cursor. Usually located to the right of the function keys, the lock keys are scattered around the keyboard. Most styles of keyboards have three LEDs indicating which locks are enabled, in the right corner above the numpad. Some ergonomic keyboards instead place the lock indicators in between the key split, some brands of keyboards have a function mode key, and may replace the scroll lock indicator with an office lock indicator. Office Lock, when enabled, will enable alternate functions of the function keys, meant for use with various word processing or email programs
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Scroll lock
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Scroll lock is a lock key on most IBM-compatible computer keyboards. Depending on the system, it may be used for different purposes. The key is not frequently used, and therefore some reduced or specialized keyboards lack Scroll Lock altogether, pressing Ctrl+Scroll Lock performs the same function as pressing Ctrl+Break. This behavior is a remnant of the original IBM PC keyboards, instead, they assigned the Pause function to Ctrl+Num Lock and the Break function to Ctrl+Scroll Lock. The Scroll Lock key was meant to lock all scrolling techniques, in the original design, Scroll Lock was intended to modify the behavior of the arrow keys. When the Scroll Lock mode was on, the keys would scroll the contents of a text window instead of moving the cursor. In this usage, Scroll Lock is a lock key like Num Lock or Caps Lock. Today, this use of Scroll Lock is rare. Modern programs honoring this behavior include IBM Lotus Notes, Forté Agent, Image-Line FL Studio, Renoise, Microsoft Excel, LibreOffice Calc, some text editors exhibit similar behavior when the arrow keys are used with a Ctrl depressed. Most GUI environments neglect Scroll Lock, which means scrolling must be accomplished with a mouse, often, the middle or the wheel mouse button works as a toggle determining if mouse movements will move the mouse cursor or scroll the contents in scroll window. Some web browsers including Firefox and Internet Explorer support a Caret browsing mode which can be toggled by F7, when Scroll Lock is pressed again the screen is unfrozen and all text generated during the freeze is printed at once. This allows the user to pause the display and read long messages that scroll through the screen too quickly to read, for example when the system is booting up. If not configured otherwise, Ctrl+S and Ctrl+Q can be used instead of Scroll Lock, in any terminal in Linux and this behaviour emulates the Hold Screen key or similar flow control mechanisms on computer terminals. The behaviour must be distinguished from pressing the Pause key during POST or under DOS, on the FreeBSD system console, the Scroll Lock key additionally enables scrolling, after pressing Scroll Lock, one can use Page Up and Page Down to scroll up or down. Pressing Scroll Lock again disables this mode and moves back to the bottom of the output, the Linux console implements this behaviour by using ⇧ Shift+Page Up and ⇧ Shift+Page Down, not requiring Scroll Lock to be active. Automatic scrolling is suspended for as long as Scroll Lock remains activated, dR-DOS7.02 and higher provides a CONFIG. SYS directive named SCROLLOCK=ON|OFF to change the Scroll Lock status on the fly. The operating system, however, will temporarily suspend any automatic timeouts in CONFIG. SYS trace and this can be accomplished by setting the REG_DWORD registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\i8042prt\Parameters\CrashOnCtrlScroll to 1. Once set, the user can hold the RCtrl key and tap the Scroll Lock key twice to trigger a Blue Screen of Death
34.
Num lock
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Num Lock or Numeric Lock is a key on the numeric keypad of most computer keyboards. It is a key, like Caps Lock and Scroll Lock. Its state affects the function of some of the keys, and is displayed by an LED built into the keyboard. The Num Lock key exists because earlier 84-key IBM PC keyboards did not have control or arrows separate from the numeric keypad. Most earlier computer keyboards had separate number keys and cursor keys, however, to reduce cost. Num Lock would be used to choose between the two functions, on some laptop computers, the Num Lock key is used to convert part of the main keyboard to act as a numeric keypad rather than letters. On some laptop computers, the Num Lock key is absent, since Apple keyboards never had a combination of arrow keys and numeric keypad, Apple has keyboards with a separate numeric keypad but no functional Num Lock key. Instead, these include a Clear key
35.
Caps lock
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Caps Lock is a button on a computer keyboard that, when pressed, causes all letters to be generated in capitals until deactivated. It is located in the position of a similar Shift lock key found in some keyboard layouts. It is usually a key, each press reverses its action. Exactly what Caps Lock does depends on the system and driver. On non-IBM PC-compatible computers it may depend on the keyboard hardware. Usually the effect is the same as pressing keys with the shift key depressed, letters are capitalised, for example, on most keyboards the 5 key generates 5 in non-shift mode and % if the shift key is pressed. If caps lock is activated the key generates % until deactivated, in other cases the key may only affect letters, so that the 5 key always generates 5 unless the shift key is pressed. Typical Caps Lock behaviour is that pressing the key sets an input mode in which all typed letters are uppercase by default, the keyboard remains in Caps Lock mode until the key is pressed again. Some keyboard layouts implement a variant, where Shift will temporarily invoke two different sets of alternative key definitions depending on if Caps Lock is currently active or not. The inverting behaviour of the Shift key is the most common variant on English keyboards, keyboards often include a small LED to indicate that Caps Lock is active, either on the key itself or in a row with Scroll lock and Num lock indicators. While on the original IBM PC keyboard this LED was controlled by the keyboard itself, some new laptop and wireless desktop keyboards lack the LED, instead providing software that gives an on-screen indicator. Typing case-sensitive passwords that are not displayed verbatim on the screen may cause mistakes when Caps Lock is on, help guides, tech support materials, and sometimes the interface itself may include advice on checking Caps Lock before typing a password. In Windows login screens, a warning that Caps Lock is on is shown in a balloon near the field, in Mac OS X, when Caps Lock is on, a Caps Lock symbol is displayed inside a password field. Operating systems may also provide audible notifications when Caps Lock, Num lock, some keyboard drivers include a configuration option to deactivate the Caps Lock key. This behaviour allows users to decide whether they want to use the key. In ex-USSR Unix community, Caps Lock key is used as input language switcher. Support for this is present in KDE, GNOME and other desktop environments, default Russian, Ukrainian layouts for FreeBSD specifies Caps Lock as input language switcher. Additional programs can be used for goal in Microsoft Windows
36.
F-Lock
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The F-Lock key, introduced by Microsoft in 2001 toggles the state of the function keys. When on, keys F1 to F12 behave as applicable, with meanings defined by the application being used at the time, when off, new behaviour is used, F5 means open, F10 means spell etc. In early models, the state reverted to off at each reboot or keyboard reset, other keyboard manufacturers have also implemented the F-Lock onto their keyboards. The introduction of F-Lock was marked by criticism on several points, first, the behaviour was unintuitive, Pressing a key such as F4 by default no longer had its normal meaning, so combinations such as Alt+F4 appeared not to work. This caused strong criticism from some commentators, Pressing F2 in Windows Explorer in attempt to rename a file would instead undo an earlier file operation, with potentially disastrous consequences if the actual effect went silently unnoticed. Because of such concerns, a number of methods for disabling the F-Lock function appeared on the web, many Windows/PC users have found a workaround using Microsofts Intellitype Pro software, which allows a user to assign keystrokes/macros to the function and accessory keys. For example, assigning a macro to the function key F1 renders the F-lock issue moot, the new behaviours assigned to the keys are as follows, F-Lock Key XML fix F-Lock Key Eliminator for Linux
37.
Arrow keys
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Cursor movement keys or arrow keys are buttons on a computer keyboard that are either programmed or designated to move the cursor in a specified direction. Arrow keys are located at the bottom of the keyboard to the left side of the numeric keypad, usually arranged in an inverted-T layout but also found in diamond shapes. Arrow keys are used for navigating around documents and for playing games. The inverted-T layout was popularized by the Digital Equipment Corporation LK201 keyboard from 1982, before the computer mouse was widespread, arrow keys were the primary way of moving a cursor on screen. Mouse keys is a feature that allows controlling a cursor with arrow keys instead. A feature echoed in the Amiga whereby holding the Amiga key would allow a person to move the pointer with the keys in the Workbench. It can be used instead of WASD keys, to games using those keys. The inverted-T layout was popularized by the Digital Equipment Corporation LK201 keyboard from 1982, some Commodore 8-bit computers used two keys instead of four, with directions selected using the shift key. The original Apple Macintosh had no keys at the insistence of Steve Jobs. Arrow keys were included in later Apple keyboards, although the arrow keys provide one convention for cursor movement on computers, there are also other conventions for cursor movement that use entirely different keys. In Power Point, an object may be moved in micro-increments by depressing Ctrl whilst using the arrow keys. This layout dates back to Sinclair ZX80, Sinclair ZX81 and Sinclair Spectrum software, WASD is a set of four keys on a QWERTY or QWERTZ computer keyboard which mimics the inverted-T configuration of the arrow keys. These keys are used to control the player characters movement in computer games, most commonly first person games but also in many driving. W/S control forward and backward, while A/D control strafing left, typically, modifier keys are not used to strafe. Primarily, WASD is used to account for the fact that the keys are not ergonomic to use in conjunction with a right-handed mouse. This also allows the user to use the left thumb to press the space bar. In later games, the usage of the E key to interact with items or open up the inventory was also popularized due to its next to the WASD keys. As opposed to the default controls of Doom or Duke Nukem 3D
38.
Page Up and Page Down keys
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The Page Up and Page Down keys are two keys commonly found on computer keyboards. The two keys are used to scroll up or down in documents, but the scrolling distance varies between different applications. In word processors, for instance, they may jump by a physical page or by a screen view that may show only part of one page or many pages at once depending on zoom factor. In cases when the document is shorter than one screenful, Page Up, operating systems differ as to whether the keys just move the view – e. g. in Mac OS X – or also the input caret – e. g. in Microsoft Windows. In right-to-left settings, PgUp will move upwards or rightwards. The keys have been dubbed previous page and next page, accordingly, the arrow keys and the scroll wheel can also be used to scroll a document, although usually by smaller incremental distances. Used together with a key, such as Alt, ⌥ Opt, ^Ctrl or a combination thereof. In most operating systems, if the Page Up or Page Down key is pressed along with the ⇧ Shift key in editable text, in some applications, the Page Up and Page Down keys behave differently in caret navigation. In August 2008, Microsoft received the patent #7,415,666 for the functions of the two keys – Page Up & Page Down
39.
Home key
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The Home key is commonly found on computer keyboards. The key has the effect of the End key. In limited-size keyboards where the Home key is missing the same functionality can be reached via the key combination of Fn+←. Its standard symbol ⇱ from ISO/IEC 9995-7, i. e. an arrow pointing to a corner in the left, is used on some full-size keyboards instead of a possibly localized text label. In modern Microsoft Windows text editing applications, it is used to return the cursor to the beginning of the line where the cursor is located. When the text is not editable, the Home key is used to return to the beginning of the document, the Home key can also be used to select all the characters before the cursor in a certain line if pressed along with ⇧ Shift in selectable text. Only full-sized Apple keyboards have a Home key, on most Mac OS X applications, the key works like the original on UNIX in the days of dumb-terminals, where Home moves to the start of a document. When the key is pressed, the scrolls to the top, while the caret position does not change at all, that is. On Apple keyboards that do not have a Home key, one can press fn+← for the Home key functionality described above, to get the same result as the Windows platform, one can press ⌘ Command+←. An application can also be used to change this behaviour, in Linux, the Home key has basically the same functionality as it does on Windows. It returns the cursor to the beginning of the line in editable text, also, like Windows, the Home key can be used to select all the characters before the cursor in a certain line if pressed along with shift in editable text. In older screen-oriented, text-based applications, the user often accessed the screen they wanted through a series of screens with numbered options. The Home key took the user to the top menu screen
