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80-513: The keyboard is optimized by character frequency . 85% of average keystrokes in English text can be typed without chording, and chords are limited to 2 fingers (opposable thumb and one finger). As a result, the FrogPad has many more keys than a GKOS or Microwriter or Baudot keyboard but fewer than a conventional computer keyboard . The founder and CEO of the company was Linda Marroquin . She left

160-472: A with acute accent ), Compose followed by A and then E results in æ ( ae ligature ), and Compose followed by O and then C results in © (circled c , copyright symbol ). The Compose key is supported by the X Window System (used by most Unix-like operating systems , including most Linux distributions ). Some keyboards have a key labeled "Compose", but any key can be configured to serve this function. For example,

240-400: A dead key by default, or sometimes a normal key can temporarily be altered to function as a dead key by simultaneously holding down the secondary-shift key— AltGr or ⌥ Option : a typical example might be AltGr + 6   a will produce â (assuming the "6" key is also the "^" key). In some systems, there is no indication to the user that a dead key has been struck, so

320-467: A dictionary. The lemma is the word in its canonical form. The second method is to include all word variants when counting, such as "abstracts", "abstracted" and "abstracting" and not just the lemma of "abstract". This second method results in letters like ⟨s⟩ appearing much more frequently, such as when counting letters from lists of the most used English words on the Internet. ⟨s⟩

400-472: A fundamental role in cryptograms and several word puzzle games, including hangman , Scrabble , Wordle and the television game show Wheel of Fortune . One of the earliest descriptions in classical literature of applying the knowledge of English letter frequency to solving a cryptogram is found in Edgar Allan Poe 's famous story " The Gold-Bug ", where the method is successfully applied to decipher

480-523: A given language, since all writers write slightly differently. However, most languages have a characteristic distribution which is strongly apparent in longer texts. Even language changes as extreme as from Old English to modern English (regarded as mutually unintelligible) show strong trends in related letter frequencies: over a small sample of Biblical passages, from most frequent to least frequent, enaid sorhm tgþlwu æcfy ðbpxz of Old English compares to eotha sinrd luymw fgcbp kvjqxz of modern English, with

560-465: A key that would temporarily interrupt the communications line. The Break key can be used by software in several different ways, such as to switch between multiple login sessions, to terminate a program, or to interrupt a modem connection. In programming, especially old DOS-style BASIC, Pascal and C, Break is used (in conjunction with Ctrl) to stop program execution. In addition to this, Linux and variants, as well as many DOS programs, treat this combination

640-405: A letter with a specific diacritic. For example, on some keyboard layouts, the grave accent key ` is a dead key: in this case, striking ` and then A results in à ( a with grave accent); ` followed by ⇧ Shift + E results in È ( E with grave accent). A grave accent in isolated form can be typed by striking ` and then Space bar . A key may function as

720-478: A lighter touch for such characters as the period or comma, which did not occupy as much area on the paper. Since an electric typewriter supplied the force to the typebar itself after the typist merely touched the key, the typewriter itself had to be designed to supply different forces for different characters. To simplify this, the most common layout for electric typewriters in the United States differed from that for

800-424: A manual typewriter. This was imperfect, as some shifted special characters were moved one key to the left, as the number zero, although on the right, was low in code sequence. Later, when computer terminals were designed from less expensive electronic components, it was not necessary to have any bits in common between the shifted and unshifted characters on a given key. This eventually led to standards being adopted for

880-562: A message giving the location of a treasure hidden by Captain Kidd . Herbert S. Zim , in his classic introductory cryptography text Codes and Secret Writing , gives the English letter frequency sequence as " ETAON RISHD LFCMU GYPWB VKJXZQ ", the most common letter pairs as "TH HE AN RE ER IN ON AT ND ST ES EN OF TE ED OR TI HI AS TO", and the most common doubled letters as "LL EE SS OO TT FF RR NN PP CC". Different ways of counting can produce somewhat different orders. Letter frequencies also have

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960-406: A modifier key is held down while another key is struck. To facilitate this, modifier keys usually come in pairs, one functionally identical key for each hand, so holding a modifier key with one hand leaves the other hand free to strike another key. An alphanumeric key labelled with only a single letter (usually the capital form) can generally be struck to type either a lower case or capital letter,

1040-412: A paragraph of text and advance an editing cursor to the start of the next available line, similar to the "carriage return" key of a typewriter. When the attached system is processing a user command line , pressing "enter" may signal that the command has been completely entered and that the system may now process it. Shift key: when one presses shift and a letter, it will capitalize the letter pressed with

1120-475: A product I can’t be proud of that lives up to what all of you expect and deserve.". Since then, the company has ceased communication. On August 14, 2014 , Frogpad founder Linda Marroquin stated that the Frogpad license to Satori Tech Solutions has expired and that she does not know why Mr. Taylor is not responding to consumers who pre-purchased products. Although she is aware of complaints filed against Mr. Taylor at

1200-587: A strong effect on the design of some keyboard layouts . The most frequent letters are placed on the home row of the Blickensderfer typewriter , the Dvorak keyboard layout , Colemak and other optimized layouts. The frequency of letters in text has been studied for use in cryptanalysis , and frequency analysis in particular, dating back to the Arab mathematician al-Kindi (c. 801–873 AD), who formally developed

1280-399: A table after measuring 40,000 words. In English, the space character occurs almost twice as frequently as the top letter ( ⟨e⟩ ) and the non-alphabetic characters (digits, punctuation, etc.) collectively occupy the fourth position (having already included the space) between ⟨t⟩ and ⟨a⟩ . The frequency of the first letters of words or names

1360-549: A type of shift key, such that one or more following characters were interpreted differently, hence the term escape sequence , which refers to a series of characters, usually preceded by the escape character . On machines running Microsoft Windows, prior to the implementation of the Windows key on keyboards, the typical practice for invoking the "start" button was to hold down the control key and press escape. This process still works in Windows 10 and 11. An "enter" key may terminate

1440-433: A variety of sources (press reporting, religious texts, scientific texts and general fiction) and there are differences especially for general fiction with the position of ⟨h⟩ and ⟨i⟩ , with ⟨h⟩ becoming more common. Different dialects of a language will also affect a letter's frequency. For example, an author in the United States would produce something in which ⟨z⟩

1520-506: A very influential electric typewriter, which was imitated by computer keyboards; and the IBM PC (1981), namely the Model M (1985), which is the basis for many modern keyboard layouts. Within a community, keyboard layout is generally quite stable, due to the high training cost of touch-typing , and the resulting network effect of having a standard layout and high switching cost of retraining, and

1600-422: Is any specific physical, visual, or functional arrangement of the keys, legends, or key-meaning associations (respectively) of a computer keyboard , mobile phone , or other computer-controlled typographic keyboard. Physical layout is the actual positioning of keys on a keyboard. Visual layout is the arrangement of the legends (labels, markings, engravings) that appear on those keys. Functional layout

1680-562: Is especially common in inflected words (non-lemma forms) because it is added to form plurals and third person singular present tense verbs. A final method is to count letters based on their frequency of use in actual texts, resulting in certain letter combinations like ⟨th⟩ becoming more common due to the frequent use of common words like "the", "then", "both", "this", etc. Absolute usage frequency measures like this are used when creating keyboard layouts or letter frequencies in old fashioned printing presses. An analysis of entries in

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1760-476: Is especially useful when using a terminal, X11 (a Unix environment included with OS X as an install option) or MS Windows . The key can generally be used to produce a secondary mouse click as well. There is also a Fn key on modern Mac keyboards, which is used for switching between use of the F1 , F2 , etc. keys either as function keys or for other functions like media control, accessing Spotlight , controlling

1840-519: Is helpful in pre-assigning space in physical files and indexes. Given 26  filing cabinet drawers, rather than a 1:1 assignment of one drawer to one letter of the alphabet, it is often useful to use a more equal-frequency-letter code by assigning several low-frequency letters to the same drawer (often one drawer is labeled VWXYZ), and to split up the most-frequent initial letters ( ⟨s, a, c⟩ ) into several drawers (often 6 drawers Aa-An, Ao-Az, Ca-Cj, Ck-Cz, Sa-Si, Sj-Sz). The same system

1920-629: Is more common than an author in the United Kingdom writing on the same topic: words like "analyze", "apologize", and "recognize" contain the letter in American English, whereas the same words are spelled "analyse", "apologise", and "recognise" in British English. This would highly affect the frequency of the letter ⟨z⟩ , as it is rarely used by British writers in the English language. The "top twelve" letters constitute about 80% of

2000-486: Is significantly different from the overall frequency of all the digits in a set of numeric data, an observation known as Benford's law . An analysis by Peter Norvig on words that appear 100,000 times or more in Google Books data transcribed using optical character recognition (OCR) determined the frequency of first letters of English words, among other things. *See İ and dotless I . The figure below illustrates

2080-399: Is the arrangement of the key-meaning association or keyboard mapping , determined in software, of all the keys of a keyboard; it is this (rather than the legends) that determines the actual response to a key press. Modern computer keyboards are designed to send a scancode to the operating system (OS) when a key is pressed or released. This code reports only the key's row and column, not

2160-559: Is to trigger the Stop button in many web browsers and operating systems. ESC was part of the standard keyboard of the Teletype Model 33 (introduced in 1964 and used with many early minicomputers). The DEC VT50 , introduced July 1974, also had an Esc key. The TECO text editor (c. 1963) and its descendant Emacs ( c.  1985 ) use the Esc key extensively. Historically it also served as

2240-505: Is used in some multi-volume works such as some encyclopedias . Cutter numbers , another mapping of names to a more equal-frequency code, are used in some libraries. Both the overall letter distribution and the word-initial letter distribution approximately match the Zipf distribution and even more closely match the Yule distribution . Often the frequency distribution of the first digit in each datum

2320-517: Is visibly different from Faulkner 's. Letter, bigram , trigram , word frequencies, word length, and sentence length can be calculated for specific authors, and used to prove or disprove authorship of texts, even for authors whose styles are not so divergent. Accurate average letter frequencies can only be gleaned by analyzing a large amount of representative text. With the availability of modern computing and collections of large text corpora , such calculations are easily made. Examples can be drawn from

2400-503: The Ctrl , Alt and AltGr keys seen on commodity keyboards, Apple Keyboards have ⌘ Cmd ( command ) and ⌥ Option keys. The ⌥ Option key is used much like the AltGr , and the ⌘ Cmd key like the Ctrl and Alt , to access menu options and shortcuts. Macs have a Ctrl key for compatibility with programs that expect a more traditional keyboard layout. It

2480-515: The Latin script , the center, alphanumeric portion of the modern keyboard is most often based on the QWERTY design by Christopher Sholes . Sholes' layout was long thought to have been laid out in such a way that common two-letter combinations were placed on opposite sides of the keyboard so that his mechanical keyboard would not jam. However, evidence for this claim has often been contested. In 2012, an argument

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2560-444: The VIC cipher or some other cipher based on a straddling checkerboard typically uses a mnemonic such as "a sin to err" (dropping the second "r") or "at one sir" to remember the top eight characters. There are three ways to count letter frequency that result in very different charts for common letters. The first method, used in the chart below, is to count letter frequency in lemmas of

2640-646: The XO laptop , which does not have a ⇪ Caps Lock . The UNIX keyboard layout also differs in the placement of the Esc key, which is to the left of 1 . Some early keyboards experimented with using large numbers of modifier keys. The most extreme example of such a keyboard, the so-called " space-cadet keyboard " found on MIT LISP machines , had no fewer than seven modifier keys: four control keys, Ctrl , Meta , Hyper , and Super , along with three shift keys, ⇧ Shift , Top , and Front . This allowed

2720-570: The language bar in Microsoft Windows ) that allow the user to easily switch between functional layouts. For example, a user with a Swedish keyboard who wishes to type more easily in German may switch to a functional layout intended for German—without regard to key markings. A touch typist skilled in the use of another language layout can use a keyboard with English-language legends if it is remapped to their familiar layout, because they rarely look at

2800-513: The layout of a keyboard may refer to its physical (arrangement of keys), visual (physical labeling of keys), or functional (software response to a key press or release) layout. Physical layouts only address tangible differences among keyboards. When a key is pressed, the keyboard does not send a message such as the A-key is depressed but rather the left-most main key of the home row is depressed . (Technically, each key has an internal reference number,

2880-451: The "bit-pairing" and "typewriter-pairing" forms of keyboards for computer terminals. The typewriter-pairing standard came under reconsideration, on the basis that typewriters have many different keyboard arrangements. The U.S. keyboard for the IBM PC, although it resembles the typewriter-pairing standard in most respects, differs in one significant respect: the braces are on the same two keys as

2960-565: The 'Start' (applications) menu. Keyboard layouts have evolved over time, usually alongside major technology changes. Particularly influential have been: the Sholes and Glidden typewriter (1874, also known as Remington No. 1), the first commercially successful typewriter, which introduced QWERTY ; its successor, the Remington No. 2 (1878), which introduced the shift key; the IBM Selectric (1961),

3040-533: The Concise Oxford dictionary, ignoring frequency of word use, gives an order of "EARIOTNSLCUDPMHGBFYWKVXZJQ". The letter-frequency table below is taken from Pavel Mička's website, which cites Robert Lewand's Cryptological Mathematics . According to Lewand, arranged from most to least common in appearance, the letters are: etaoinshrdlcumwfgypbvkjxqz . Lewand's ordering differs slightly from others, such as Cornell University Math Explorer's Project, which produced

3120-556: The No. 1 (1874)—though 1 and 0 were added later—shifted keys date in some cases to the No. 2 (1878), in other cases to the Selectric (1961), and modifier key placement largely dates to the Model M (1985); function key placement typically dates to the Model M, but varies significantly, particularly on laptops. The earliest mechanical keyboards were used in musical instruments to play particular notes. With

3200-447: The OS when connected (though the user is still able to reset this at will). Today, most keyboards use one of three different physical layouts, usually referred to as simply ISO ( ISO/IEC 9995 -2), ANSI ( ANSI - INCITS 154-1988), and JIS ( JIS X 6002-1980), referring roughly to the organizations issuing the relevant worldwide, United States, and Japanese standards, respectively. (In fact,

3280-613: The Texas AG and IC3, her stated intention is "to regain the brand after I get additional funding." Frequency of letters Letter frequency is the number of times letters of the alphabet appear on average in written language . Letter frequency analysis dates back to the Arab mathematician Al-Kindi ( c.  801 –873 AD), who formally developed the method to break ciphers . Letter frequency analysis gained importance in Europe with

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3360-572: The above discrepancies between functional and visual layouts. A keyboard overlay is a plastic or paper masks that can be placed over the empty space between the keys, providing the user with the functional use of various keys. Alternatively, a user applies keyboard stickers with an extra imprinted language alphabet and adds another keyboard layout via language support options in the operating system. The visual layout of any keyboard can also be changed by simply replacing its keys or attaching labels to them, such as to change an English-language keyboard from

3440-417: The advent of the printing telegraph , a keyboard was needed to select characters. Some of the earliest printing telegraph machines either used a piano keyboard outright or a layout similar to a piano keyboard. The Hughes-Phelps printing telegraph piano keyboard laid keys A-N in left-to-right order on the black piano keys, and keys O-Z in right-to-left order on the white piano keys below. In countries using

3520-570: The brackets, as their shifts. This innovation predated the IBM Personal Computer by several years. IBM adopted the 101/102 key layout on the PS/2 in 1987 (after previously using an 84-key keyboard that did not have a separate cursor and numeric keypads). Most modern keyboards basically conform to the layout specifications contained in parts 1, 2, and 5 of the international standard series ISO/IEC 9995 . These specifications were first defined by

3600-520: The character keys, a keyboard incorporates special keys that do nothing by themselves but modify the functions of other keys. For example, the ⇧ Shift key can be used to alter the output of character keys, whereas the Ctrl ( control ), Alt ( alternate ) and AltGr ( alternative graphic ) keys trigger special operations when used in concert with other keys. (Apple keyboards have differently labelled but equivalent keys, see below). Typically,

3680-452: The character keys. The core section of a keyboard consists of character keys, which can be used to type letters and other characters. Typically, there are three rows of keys for typing letters and punctuation , an upper row for typing digits and special symbols, and the Space bar on the bottom row. The positioning of the character keys is similar to the keyboard of a typewriter . Besides

3760-860: The compact models have 79, 78, and 80. The visual layout includes the symbols printed on the physical keycaps. Visual layouts vary by language, country, and user preference, and any one physical and functional layout can be employed with a number of different visual layouts. For example, the "ISO" keyboard layout is used throughout Europe, but typical French, German, and UK variants of physically identical keyboards appear different because they bear different legends on their keys. Even blank keyboards—with no legends—are sometimes used to learn typing skills or by user preference. Some users choose to attach custom labels on top of their keycaps. This can be, e.g., for masking foreign layouts, adding additional information such as shortcuts , learning aids, gaming controls, or solely for decorational purposes. The functional layout of

3840-530: The company in 2008. The original FrogPads on the market at this time were intended to be used with mobile phones and supported only Bluetooth. Two attempts to relaunch the Frogpad had been made. The first was made in February 2012 by Frogpad and Linda Marroquin. However, due to funding difficulties, this launch was canceled and the cost of pre-ordered units was refunded to customers in June 2012. The second relaunch attempt

3920-508: The cursor in the icon is not present, showing the menu only. This key was created at the same time as the Windows key. This key is normally used when the right mouse button is not present on the mouse. Some Windows public terminals do not have a Menu key on their keyboard to prevent users from right-clicking (however, in many Windows applications, a similar functionality can be invoked with the Shift+F10 keyboard shortcut ). The Windows key opens

4000-457: The desired symbol key). The Menu key or Application key is a key found on Windows-oriented computer keyboards: on Apple keyboard the same function is provided by the Command key (labelled ⌘). It is used to launch a context menu with the keyboard rather than with the usual right mouse button. The key's symbol is usually a small icon depicting a cursor hovering above a menu. On some Samsung keyboards

4080-417: The development of movable type in 1450 AD, where one must estimate the amount of type required for each letterform . Linguists use letter frequency analysis as a rudimentary technique for language identification , where it is particularly effective as an indication of whether an unknown writing system is alphabetic, syllabic , or ideographic . The use of letter frequencies and frequency analysis plays

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4160-519: The frequency distributions of the 26 most common Latin letters across some languages. All of these languages use a similar 25+ character alphabet. Based on these tables, the ' etaoin shrdlu ' equivalent for each language is as follows: Useful tables for single letter, digram, trigram, tetragram, and pentagram frequencies based on 20,000 words that take into account word-length and letter-position combinations for words 3 to 7 letters in length: Keyboard layout A keyboard layout

4240-527: The functions of other keys, navigation keys for moving the text cursor on the screen, function keys and system command keys —such as Esc and Break —for special actions, and often a numeric keypad to facilitate calculations. There is some variation between different keyboard models in the physical layout—i.e., how many keys there are and how they are positioned on the keyboard. However, differences between national layouts are mostly due to different selections and placements of symbols on

4320-497: The key appears dead, but in some text-entry systems the diacritical mark is displayed along with an indication that the system is waiting for another keystroke: either the base character to be marked, an additional diacritical mark, or Space bar to produce the diacritical mark in isolation. Compared with the secondary-shift modifier key, the dead-key approach may be a little more complicated, but it allows more additional letters. Using AltGr, only one or (if used simultaneously with

4400-449: The keyboard refers to the mapping between a physical key (such as the A key) and a consequent software event (such as the letter "A" appearing on the screen). Usually the functional layout is set (in the system configuration ) to match the visual layout of the keyboard being used, so that pressing a key will produce the expected result, corresponding to the legends on the keyboard. However, most operating systems have software (such as

4480-417: The keyboard when typing. Functional layouts can be redefined or customized within the operating system, by reconfiguring the operating system keyboard driver, or with the use of a separate software application, or by transliteration (where letters in another language get mapped to visible Latin letters on the keyboard by the way they sound). Mixed hardware-to-software keyboard extensions exist to overcome

4560-402: The keys to be on three-quarter [ 3 ⁄ 4 , or 0.75] inch centers (about 19 mm, versus musical piano keys which are 23.5 mm or about 0.93 inches wide). 0.75 inches has turned out to be optimum for fast key entry by the average-size hand, and keyboards with this key size are called "full-sized keyboards". On a manual typewriter, the operator could press the key down with

4640-713: The latter requiring the simultaneous holding of the ⇧ Shift key. The ⇧ Shift key is also used to type the upper of two symbols engraved on a given key, the lower being typed without using the modifier key. The Latin alphabet keyboard has a dedicated key for each of the letters A–Z, keys for punctuation and other symbols, usually a row of function keys , often a numeric keypad and some system control keys. In most languages except English, additional letters (some with diacritics ) are required and some are present as standard on each national keyboard, as appropriate for its national language. These keyboards have another modified key, labelled AltGr (alternative graphic), to

4720-600: The method (the ciphers breakable by this technique go back at least to the Caesar cipher used by Julius Caesar , so this method could have been explored in classical times). Letter frequency analysis gained additional importance in Europe with the development of movable type in 1450 AD, where one must estimate the amount of type required for each letterform, as evidenced by the variations in letter compartment size in typographer's type cases. No exact letter frequency distribution underlies

4800-458: The modern QWERTY layout. Sholes' chief improvement was thus to lay out the keys in rows offset horizontally from each other by three-eighths, three-sixteenths, and three-eighths inches to provide room for the levers and to reduce hand-movement distance. Although it has been demonstrated that the QWERTY layout is not the most efficient layout for typing, it remains the standard. Sholes chose the size of

4880-654: The most extreme differences concerning letterforms not shared. Linotype machines for the English language assumed the letter order, from most to least common, to be etaoin shrdlu cmfwyp vbgkqj xz based on the experience and custom of manual compositors. The equivalent for the French language was elaoin sdrétu cmfhyp vbgwqj xz . Arranging the alphabet in Morse into groups of letters that require equal amounts of time to transmit, and then sorting these groups in increasing order, yields e it san hurdm wgvlfbk opxcz jyq . Letter frequency

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4960-545: The normal shift key) two additional letters with each key, whereas using a dead key, a specific diacritic can be attached to a range of different base letters. A Compose key can be characterized as a generic dead key that may in some systems be available instead of or in addition to the more specific dead keys. It allows access to a wide range of predefined extra characters by interpreting a whole sequence of keystrokes following it. For example, striking Compose followed by ' ( apostrophe ) and then A results in á (

5040-429: The one most common on manual typewriters. Single-quote and double-quote, instead of being above the keys for the digits 2 and 8 respectively, were placed together on a key of their own. The underscore, another light character, replaced the asterisk above the hyphen. The ASCII communications code was designed so that characters on a mechanical teletypewriter keyboard could be laid out in a manner somewhat resembling that of

5120-578: The otherwise redundant right-hand ⊞ Win key may, when available, be used for this purpose. This can be emulated in Windows with third party programs, for example WinCompose. Depending on the application, some keyboard keys are not used to enter a printable character but instead are interpreted by the system as a formatting, mode shift, or special commands to the system. The following examples are found on personal computer keyboards. The system request ( SysRq ) and print screen ( PrtSc or on some keyboards e.g. PrtScn ) commands often share

5200-535: The physical layouts referred such as "ISO" and "ANSI" comply with the primary recommendations in the named standards, while each of these standards in fact also allows the other.) Keyboard layout in this sense may refer either to this broad categorization or to finer distinctions within these categories. For example, as of May 2008 , Apple Inc . produces ISO, ANSI, and JIS desktop keyboards, each in both extended and compact forms. The extended keyboards have 110, 109, and 112 keys (ISO, ANSI, and JIS, respectively), and

5280-506: The right of the space bar. (US keyboards just have a second Alt key in this position). It can be used to type an extra symbol in addition to the two otherwise available with an alphanumeric key, and using it simultaneously with the ⇧ Shift key usually gives access to a fourth symbol. These third-level and fourth-level symbols may be engraved on the right half of the key top, or they may be unmarked. Cyrillic alphabet and Greek alphabet keyboards have similar arrangements. Instead of

5360-409: The same as Ctrl+C. On modern keyboards, the break key is usually labeled Pause/Break. In most Microsoft Windows environments, the key combination Windows Pause brings up the system properties. The escape key (often abbreviated Esc) "nearly all of the time" signals Stop , QUIT , or let me "get out of a dialog" (or pop-up window). Another common application today of the Esc key

5440-516: The same key. SysRq was used in earlier computers as a "panic" button to recover from crashes (and it is still used in this sense to some extent by the Linux kernel ; see Magic SysRq key ). The print screen command is used to capture the entire screen and send it to the printer, but in the present, it usually puts a screenshot in the clipboard . The Break key /Pause key no longer has a well-defined purpose. Its origins go back to teleprinter users, who wanted

5520-494: The scan code, and these numbers are what is sent to the computer when a key is pressed or released.) The keyboard and the computer each have no information about what is marked on that key, and it could equally well be the letter A or the digit 9 . Historically, the user of the computer was requested to identify the functional layout of the keyboard when installing or customizing the operating system . Modern USB keyboards are plug-and-play ; they communicate their visual layout to

5600-477: The shift key. Another use is to type more symbols than appear to be available, for instance the semi-colon key is accompanied with a colon symbol on the top. To type a semi-colon, the key is pressed without pressing any other key. To type a colon, both this key and the Shift key are pressed concurrently. (Some systems make provision for users with mobility impairment by allowing the Shift key to be pressed first and then

5680-526: The specific character engraved on that key. The OS converts the scancode into a specific binary character code using a "scancode to character" conversion table, called the keyboard mapping table. This means that a physical keyboard may be dynamically mapped to any layout without switching hardware components—merely by changing the software that interprets the keystrokes. Often, a user can change keyboard mapping in system settings. In addition, software may be available to modify or extend keyboard functionality. Thus

5760-406: The symbol shown on the physical key-top need not be the same as appears on the screen or goes into a document being typed. Modern USB keyboards are plug-and-play ; they communicate their (default) visual layout to the OS when connected (though the user is still able to reset this at will). A computer keyboard consists of alphanumeric or character keys for typing, modifier keys for altering

5840-451: The total usage. The "top eight" letters constitute about 65% of the total usage. Letter frequency as a function of rank can be fitted well by several rank functions, with the two-parameter Cocho/Beta rank function being the best. Another rank function with no adjustable free parameter also fits the letter frequency distribution reasonably well (the same function has been used to fit the amino acid frequency in protein sequences. ) A spy using

5920-523: The ubiquity of the QWERTY layout is a case study in switching costs. Nevertheless, significant market forces can result in changes (as in Turkish adoption of QWERTY), and non-core keys are more prone to change, as they are less frequently used and less subject to the lock-in of touch-typing. The main, alphanumeric portion is typically stable, while symbol keys and shifted key values change somewhat, modifier keys more so, and function keys most of all: QWERTY dates to

6000-716: The user group at AFNOR in 1984 working under the direction of Alain Souloumiac. Based on this work, a well-known ergonomic expert wrote a report which was adopted at the ISO Berlin meeting in 1985 and became the reference for keyboard layouts. The 104/105-key PC keyboard was born when two ⊞ Win keys and a ≣ Menu key were added on the bottom row (originally for the Microsoft Windows operating system). Newer keyboards may incorporate even further additions, such as Internet access (World Wide Web navigation) keys and multimedia (access to media players) buttons. As noted before,

6080-445: The user to type over 8000 possible characters by playing suitable "chords" with many modifier keys pressed simultaneously. A dead key is a special kind of a modifier key that, instead of being held while another key is struck, is pressed and released before the other key. The dead key does not generate a character by itself, but it modifies the character generated by the key struck immediately after, typically making it possible to type

6160-450: The volume, or handling Mission Control . Fn key can be also found on smaller Windows and Linux laptops and tablets, where it serves a similar purpose. Many Unix workstations (and also home computers like the Amiga ) keyboards placed the Ctrl key to the left of the letter A , and the ⇪ Caps Lock key in the bottom left. This position of the Ctrl key is also used on

6240-407: Was advanced by two Japanese historians of technology showing that the key order on the earliest Sholes prototypes in fact followed the left-right and right-left arrangement of the contemporary Hughes-Phelps printing telegraph, described above. Later iterations diverged progressively for various technical reasons, and strong vestiges of the left-right A-N, right-left O-Z arrangement can still be seen in

6320-554: Was made by Andrew Taylor of IT consulting firm Satori Tech Solutions and began to advertise in November 2013 and solicit pre-orders in January 2014 for a "prototype" version to be delivered in February and a final production version in April of that year. However, neither version of the keyboards shipped, and a post on the company Facebook page from 20 May 2014 states that they "... WILL NOT ship

6400-689: Was used by other telegraph systems, such as the Murray Code . Similar ideas are used in modern data-compression techniques such as Huffman coding . Letter frequencies, like word frequencies , tend to vary, both by writer and by subject. For instance, ⟨d⟩ occurs with greater frequency in fiction, as most fiction is written in past tense and thus most verbs will end in the inflectional suffix -ed / -d . One cannot write an essay about x-rays without using ⟨x⟩ frequently. Different authors have habits which can be reflected in their use of letters. Hemingway 's writing style, for example,

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