It describes 18 elements comprising the initial simple design of HTML. Except for the hyperlink tag, these were influenced by SGMLguid, an in-house Standard Generalized Markup Language -based documentation format at CERN. Eleven of these elements still exist in HTML 4. HTML is a markup language that web browsers use to interpret and compose text and other material into visual or audible web pages. Default characteristics for every item of HTML markup are defined in the browser, these characteristics can be altered or enhanced by the web page designer's additional use of CSS. Many of the text elements are found in the 1988 ISO technical report TR 9537 Techniques for using SGML, which in turn covers the features of early text formatting languages such as that used by the RUNOFF command developed in the early 1960s for the CTSS operating system: these formatting commands were derived from the commands used by typesetters to manually format documents. However, the SGML concept of generalized markup is based on elements rather than print effects, with the separation of structure and markup.
Berners-Lee considered HTML to be an application of SGML. It was formally defined as such by the Internet Engineering Task Force with the mid-1993 publication of the first proposal for an HTML specification, the "Hypertext Markup Language" Internet Draft by Berners-Lee and Dan Connolly, which included an SGML Document type definition to define the grammar; the draft expired after six months, but was notable for its acknowledgment of the NCSA Mosaic browser's custom tag for embedding in-line images, reflecting the IETF's philosophy of basing standards on successful prototypes. Dave Raggett's competing Internet-Draft, "HTML+", from late 1993, suggested standardizing already-implemented features like tables and fill-out forms. After the HTML and HTML+ drafts expired in early 1994, the IETF created an HTML Working Group, which in 1995 completed "HTML 2.0", the first HTML specification intended to be treated as a standard against which future implementations should be based. Further development under the auspices of the IETF was stalled by competing interests.
Since 1996, the HTML specifications have been maintained, with input from commercial software vendors, by the World Wide Web Consortium. However, in 2000, HTML became an international standard. HTML 4.01 was published in late 1999, with further errata published through 2001. In 2004, development began on HTML5 in the Web Hypertext Application Technology Working Group, which became a joint deliverable with the W3C in 2008, completed and standardized on 28 October 2014. November 24, 1995 HTML 2.0 was published as RFC 1866. Supplemental RFCs added capabilities: November 25, 1995: RFC 1867 May 1996: RFC 1942 August 1996: RFC 1980 January 1997: RFC 2070 January 14, 1997 HTML 3.2 was published as a W3C Recommendation. It was the first version developed and standardized by the W3C, as the IETF had closed its HTML Working Group on September 12, 1996. Code-named "Wilbur", HTML 3.2 dropped math formulas reconciled overlap among various proprietary extensions and adopted most of Netscape's visual markup tags.
Netscape's blink element and Microsoft's marquee element were omitted due to a mutual agreement between the two companies. A markup for mathematical formu
Telecommunication is the transmission of signs, messages, writings and sounds or information of any nature by wire, optical or other electromagnetic systems. Telecommunication occurs when the exchange of information between communication participants includes the use of technology, it is transmitted either electrically over physical media, such as cables, or via electromagnetic radiation. Such transmission paths are divided into communication channels which afford the advantages of multiplexing. Since the Latin term communicatio is considered the social process of information exchange, the term telecommunications is used in its plural form because it involves many different technologies. Early means of communicating over a distance included visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, optical heliographs. Other examples of pre-modern long-distance communication included audio messages such as coded drumbeats, lung-blown horns, loud whistles. 20th- and 21st-century technologies for long-distance communication involve electrical and electromagnetic technologies, such as telegraph and teleprinter, radio, microwave transmission, fiber optics, communications satellites.
A revolution in wireless communication began in the first decade of the 20th century with the pioneering developments in radio communications by Guglielmo Marconi, who won the Nobel Prize in Physics in 1909, other notable pioneering inventors and developers in the field of electrical and electronic telecommunications. These included Charles Wheatstone and Samuel Morse, Alexander Graham Bell, Edwin Armstrong and Lee de Forest, as well as Vladimir K. Zworykin, John Logie Baird and Philo Farnsworth; the word telecommunication is a compound of the Greek prefix tele, meaning distant, far off, or afar, the Latin communicare, meaning to share. Its modern use is adapted from the French, because its written use was recorded in 1904 by the French engineer and novelist Édouard Estaunié. Communication was first used as an English word in the late 14th century, it comes from Old French comunicacion, from Latin communicationem, noun of action from past participle stem of communicare "to share, divide out.
Homing pigeons have been used throughout history by different cultures. Pigeon post had Persian roots, was used by the Romans to aid their military. Frontinus said; the Greeks conveyed the names of the victors at the Olympic Games to various cities using homing pigeons. In the early 19th century, the Dutch government used the system in Sumatra, and in 1849, Paul Julius Reuter started a pigeon service to fly stock prices between Aachen and Brussels, a service that operated for a year until the gap in the telegraph link was closed. In the Middle Ages, chains of beacons were used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could only pass a single bit of information, so the meaning of the message such as "the enemy has been sighted" had to be agreed upon in advance. One notable instance of their use was during the Spanish Armada, when a beacon chain relayed a signal from Plymouth to London. In 1792, Claude Chappe, a French engineer, built the first fixed visual telegraphy system between Lille and Paris.
However semaphore suffered from the need for skilled operators and expensive towers at intervals of ten to thirty kilometres. As a result of competition from the electrical telegraph, the last commercial line was abandoned in 1880. On 25 July 1837 the first commercial electrical telegraph was demonstrated by English inventor Sir William Fothergill Cooke, English scientist Sir Charles Wheatstone. Both inventors viewed their device as "an improvement to the electromagnetic telegraph" not as a new device. Samuel Morse independently developed a version of the electrical telegraph that he unsuccessfully demonstrated on 2 September 1837, his code was an important advance over Wheatstone's signaling method. The first transatlantic telegraph cable was completed on 27 July 1866, allowing transatlantic telecommunication for the first time; the conventional telephone was invented independently by Alexander Bell and Elisha Gray in 1876. Antonio Meucci invented the first device that allowed the electrical transmission of voice over a line in 1849.
However Meucci's device was of little practical value because it relied upon the electrophonic effect and thus required users to place the receiver in their mouth to "hear" what was being said. The first commercial telephone services were set-up in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven and London. Starting in 1894, Italian inventor Guglielmo Marconi began developing a wireless communication using the newly discovered phenomenon of radio waves, showing by 1901 that they could be transmitted across the Atlantic Ocean; this was the start of wireless telegraphy by radio. Voice and music had little early success. World War I accelerated the development of radio for military communications. After the war, commercial radio AM broadcasting began in the 1920s and became an important mass medium for entertainment and news. World War II again accelerated development of radio for the wartime purposes of aircraft and land communication, radio navigation and radar. Development of stereo FM broadcasting of radio
The VT100 is a video terminal, introduced in August 1978 by Digital Equipment Corporation. It was one of the first terminals to support ANSI escape codes for cursor control and other tasks, added a number of extended codes for special features like controlling the status lights on the keyboard; this led to rapid uptake of the ANSI standard, becoming the de facto standard for terminal emulators. The VT100s the VT102, was successful in the market, made DEC the leading terminal vendor; the VT100 series was replaced by the VT200 series starting in 1983. Over six million terminals in the VT series would be sold, based on the success of the VT100s. DEC's first successful video terminal was the VT50, introduced in 1974 and replaced by the VT52 in 1975; the VT52 featured a text display with 80 columns and 24 rows, bidirectional scrolling, a custom control language that allowed the cursor to be moved about the screen. These "smart terminals" were a hit both due to their capabilities and their ability to be run over inexpensive serial links, rather than custom connection as in the case of systems like the IBM 3270 that required expensive controllers for distributed applications.
The VT100 was introduced in August 1978. Like the earlier models, it communicated with its host system over serial lines at a minimum speed of 50 bit/s, but increased the maximum speed to doubled that of the VT52 at 19,200 bit/s. Basic improvements on the VT52 included a 132 column mode, a variety of "graphic renditions" including blinking, reverse video, underlining; the VT100 introduced an additional box-drawing character set containing various pseudographics that allowed the drawing of on-screen forms. All setup of the VT100 was accomplished using interactive displays presented on the screen. Maintainability was significantly improved since a VT100 could be disassembled without use of tools; the major change within the system was the control system. Unlike the VT50/52's proprietary cursor control language, the VT100 was based on the emerging ANSI X3.64 standard for command codes. At the time, computer vendors suggested that the standard was beyond the state of the art and could not be implemented at a reasonable price point.
The introduction of low-cost microprocessors and the ever-falling cost of computer memory addressed these problems, the VT100 used the new Intel 8080 as its internal processor. In addition, the VT100 provided backwards compatibility for VT52 users, with support for the VT52 control sequences. In 1983, the VT100 was replaced by the more-powerful VT200 series terminals such as the VT220; the VT100 was the first of Digital's terminals to be based on an industry-standard microprocessor, the Intel 8080. Options could be added to the terminal to support an external printer, additional graphic renditions, more memory; the option, known as Advanced Video Option or AVO, allowed the terminal to support a full 24 lines of text in 132 column mode. The VT100 became a platform; the VT101 and VT102 were non-expandable follow-on versions. The VT101 was a base-model VT100, while the VT102 came standard with the AVO and serial printer port options pre-installed; the VT105 contained a simple graphics subsystem known as waveform graphics, compatible with same system in the earlier VT55.
This system allowed two mathematical functions to be drawn to the screen on top of the normal text display, allowing text and graphics to be mixed to produce charts and similar output. The VT125 added an implementation of the byte-efficient Remote Graphic Instruction Set, ReGIS, which used custom ANSI codes to send the graphics commands to the terminal, rather than requiring the terminal to be set to a separate graphics mode like the VT105; the VT100 form factor left significant room in the case for expansion, DEC used this to produce several all-in-one stand-alone minicomputer systems. The VT103 included a cardcage and 4×4 Q-Bus backplane, sufficient to configure a small LSI-11 system within the case, supported an optional dual TU58 DECtape II block addressable cartridge tape drive which behaves like a slow disk drive; the VT180 added a single-board microcomputer using a Zilog Z80 to run CP/M. The VT278 added a PDP-8 processor, allowing the terminal to run Digital's WPS-8 word processing software.
DEC Special Graphics Notes DEC video terminal history VT100 user guide VT100 Series Technical Manual ECMA-48 The DEC category at the Terminals Wiki
A computer terminal is an electronic or electromechanical hardware device, used for entering data into, displaying or printing data from, a computer or a computing system. The teletype was an example of an early day hardcopy terminal, predated the use of a computer screen by decades; the acronym CRT, which once referred to a computer terminal, has come to refer to a type of screen of a personal computer. Early terminals were inexpensive devices but slow compared to punched cards or paper tape for input, but as the technology improved and video displays were introduced, terminals pushed these older forms of interaction from the industry. A related development was timesharing systems, which evolved in parallel and made up for any inefficiencies of the user's typing ability with the ability to support multiple users on the same machine, each at their own terminal; the function of a terminal is confined to input of data. A terminal that depends on the host computer for its processing power is called a "dumb terminal" or a thin client.
A personal computer can run terminal emulator software that replicates the function of a terminal, sometimes allowing concurrent use of local programs and access to a distant terminal host system. The terminal of the first working programmable automatic digital Turing-complete computer, the Z3, had a keyboard and a row of lamps to show results. Early user terminals connected to computers were electromechanical teleprinters/teletypewriters, such as the Teletype Model 33 ASR used for telegraphy or the Friden Flexowriter. Keyboard/printer terminals that came included the IBM 2741 and the DECwriter LA30. Respective top speeds of teletypes, IBM 2741 and LA30 were 15 and 30 characters per second. Although at that time "paper was king" the speed of interaction was limited. Early video computer displays were sometimes nicknamed "Glass TTYs" or "Visual Display Units", used no CPU, instead relying on individual logic gates or primitive LSI chips, they became popular Input-Output devices on many different types of computer system once several suppliers gravitated to a set of common standards: ASCII character set, but early/economy models supported only capital letters RS-232 serial ports 24 lines of 80 characters of text.
Models sometimes had two character-width settings. Some type of cursor that can be positioned. Implementation of at least 3 control codes: Carriage Return, Line-Feed, Bell, but many more, such as Escape sequences to provide underlining, dim or reverse-video character highlighting, to clear the display and position the cursor; the Datapoint 3300 from Computer Terminal Corporation was announced in 1967 and shipped in 1969, making it one of the earliest stand-alone display-based terminals. It solved the memory space issue mentioned above by using a digital shift-register design, using only 72 columns rather than the more common choice of 80. Starting with the Datapoint 3300, by the late 1970s and early 1980s, there were dozens of manufacturers of terminals, including Lear-Siegler, ADDS, Data General, DEC, Hazeltine Corporation, Heath/Zenith, Hewlett Packard, IBM, Volker-Craig, Wyse, many of which had incompatible command sequences; the great variations in the control codes between makers gave rise to software that identified and grouped terminal types so the system software would display input forms using the appropriate control codes.
The great majority of terminals were monochrome, manufacturers variously offering green, white or amber and sometimes blue screen phosphors.. Terminals with modest color capability were available but not used. An "intelligent" terminal does its own processing implying a microprocessor is built in, but not all terminals with microprocessors did any real processing of input: the main computer to which it was attached would have to respond to each keystroke; the term "intelligent" in this context dates from 1969. Notable examples include the IBM 2250 and IBM 2260, predecessors to the IBM 3270 and introduced with System/360 in 1964. Most terminals were connected to minicomputers or mainframe computers and had a green or amber screen. Terminals communicate wi
The percent sign is the symbol used to indicate a percentage, a number or ratio as a fraction of 100. Related signs include the permille sign ‰ and the permyriad sign ‱, which indicate that a number is divided by one thousand or ten thousand respectively. Higher proportions use parts-per notation. English style guides prescribe writing the percent sign following the number without any space between. However, the International System of Units and ISO 31-0 standard prescribe a space between the number and percent sign, in line with the general practice of using a non-breaking space between a numerical value and its corresponding unit of measurement. Other languages have other rules for spacing in front of the percent sign: In Czech and in Slovak, the percent sign is spaced with a non-breaking space if the number is used as a noun, whereas no space is inserted if the number is used as an adjective. In Finnish, the percent sign is always spaced, a case suffix can be attached to it using the colon.
In French, the percent sign must be spaced with a non-breaking space. In Italian, the percent sign is never spaced. In Spanish, the percent sign must always be spaced now, as every other symbol. In Russian, the percent sign is spaced, contrary to the guidelines of the GOST 8.417-2002 state standard. In Chinese, the percent sign is never spaced because Chinese does not use spaces to separate characters or words at all. According to the Swedish Language Council, the percent sign should be preceded by a space in Swedish, as all other units. In German, the space is prescribed by the regulatory body in the national standard DIN 5008. In Turkish and other Turkic languages, the percent sign precedes rather than follows the number, without an intervening space. In Persian texts, the percent sign may either precede or follow the number, in either case without a space. In Arabic, the percent sign follows the number. In Hebrew, the percent sign precedes the number without intervening space, it is recommended that the percent sign only be used in tables and other places with space restrictions.
In running text, it should be spelled out per cent. For example, not "Sales increased by 24% over 2006", but rather "Sales increased by 24 percent over 2006". Prior to 1425 there is no known evidence of a special symbol being used for percentage; the Italian term per cento, "for a hundred", was used as well as several different abbreviations. Examples of this can be seen in the 1339 arithmetic text depicted below; the letter p with its descender crossed by a horizontal or diagonal strike conventionally stood for per, par, or pur in Mediaeval and Renaissance palaeography. At some point a scribe of some sort used the abbreviation "pc" with a tiny loop or circle This appears in some additional pages of a 1425 text which were added around 1435; this is shown below. The "pc" with a loop evolved into a horizontal fraction sign by 1650 and thereafter lost the "per". In 1925 D. E. Smith wrote, "The solidus form is modern." The Unicode code points are: U+0025 % PERCENT SIGN, U+2030 ‰ PER MILLE SIGN, U+2031 ‱ PER TEN THOUSAND SIGN a.k.a. basis point, U+FF05 ％ FULLWIDTH PERCENT SIGN U+FE6A ﹪ SMALL PERCENT SIGN There is U+066A ٪ ARABIC PERCENT SIGN, which has the circles replaced by square dots set on edge, the shape of the digit 0 in Arabic numerals.
The ASCII code for the percent character is 0x25 in hexadecimal. Names for the percent sign include percent sign, mod and the humorous double-oh-seven. In computing, the percent character is used for the modulo operation in programming languages that derive their syntax from the C programming language, which in turn acquired this usage from the earlier B. In the textual representation of URIs, a % followed by a 2-digit hexadecimal number denotes an octet specifying a character that might otherwise not be allowed in URIs. In SQL, the percent sign is a wildcard character in "LIKE" expressions, for example SELECT * FROM table WHERE fullname LIKE'Lisa %' will fetch all records whose names start with "Lisa ". In TeX and PostScript, in GNU Octave and MATLAB, a % denotes a line comment. In BASIC, a trailing % after a variable name marks it as an integer. In Perl % is the sigil for hashes. In many programming languages' string formatting operations, the percent sign denotes parts of the template string that will be replaced with arguments.
In Python and Ruby the percent sign is used as the string formatting operator. In the command processors COMMAND. COM and CMD. EXE, %1, %2... stand for the first, second... parameters of a batch file. % 0 stands for the specification of the batch file itself. The % sign is used in the FOR command. %VAR1% represents the value of
Cursor (user interface)
In computer user interfaces, a cursor is an indicator used to show the current position for user interaction on a computer monitor or other display device that will respond to input from a text input or pointing device. The mouse cursor is called a pointer, owing to its resemblance in usage to a pointing stick. Cursor is Latin for'runner.' A cursor is the name given to the transparent slide engraved with a hairline, used for marking a point on a slide rule. The term was transferred to computers through analogy. In most command-line interfaces or text editors, the text cursor known as a caret, is an underscore, a solid rectangle, or a vertical line, which may be flashing or steady, indicating where text will be placed when entered. In text mode displays, it was not possible to show a vertical 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, the vertical bar is used instead. In a typical text editing application, the cursor can be moved by pressing various keys; these include the four arrow keys, the Page Up and Page Down keys, the Home key, the End key, various key combinations involving a modifier key such as the Control key. The position of the cursor may be changed by moving the mouse pointer to a different location in the document and clicking; the blinking of the text cursor is temporarily suspended when it is being moved. Some interfaces use an underscore or thin vertical bar to indicate that the user is in insert mode, a mode where text will be inserted in the middle of the existing text, a larger block to indicate that the user is in overtype mode, where inserted text will overwrite existing text. In this way, a block cursor may be seen as a piece of selected text one character wide, since typing will replace the text "in" the cursor with the new text.
A vertical line text cursor with a small left-pointing or right-pointing appendage are for indicating the direction of text flow on systems that support bi-directional text, is thus known among programmers as a'bidi cursor'. 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 pointer or mouse cursor echoes movements of the pointing device a mouse, touchpad or trackball. This kind of cursor is used to manipulate elements of graphical user interfaces such as menus, scrollbars or any other widget, it may be called a "mouse pointer," because the mouse is the dominant type of pointing device used with desktop computers. The I-beam pointer is a cursor shaped like a serifed capital letter "I"; the purpose of this cursor is to indicate that the text beneath the cursor can be highlighted, sometimes inserted or changed. The idea of a cursor being used as a marker or insertion point for new data or transformations, such as rotation, can be extended to a 3D modeling environment.
Blender, for instance, uses a 3D cursor to determine. 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
In mathematics and computing, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most the symbols "0"–"9" to represent values zero to nine, "A"–"F" to represent values ten to fifteen. Hexadecimal numerals are used by computer system designers and programmers, as they provide a more human-friendly representation of binary-coded values; each hexadecimal digit represents four binary digits known as a nibble, half a byte. For example, a single byte can have values ranging from 0000 0000 to 1111 1111 in binary form, which can be more conveniently represented as 00 to FF in hexadecimal. In mathematics, a subscript is used to specify the radix. For example the decimal value 10,995 would be expressed in hexadecimal as 2AF316. In programming, a number of notations are used to support hexadecimal representation involving a prefix or suffix; the prefix 0x is used in C and related languages, which would denote this value by 0x2AF3. Hexadecimal is used in the transfer encoding Base16, in which each byte of the plaintext is broken into two 4-bit values and represented by two hexadecimal digits.
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; some authors prefer a text subscript, such as 159decimal and 159hex, or 159h. In linear text systems, such as those used in most computer programming environments, a variety of methods have arisen: In URIs, character codes are written as hexadecimal pairs prefixed with %: http://www.example.com/name%20with%20spaces where %20 is the space character, ASCII code point 20 in hex, 32 in decimal. In XML and XHTML, characters can be expressed as hexadecimal numeric character references using the notation
ode, thus ’. In the Unicode standard, a character value is represented with U+ followed by the hex value, e.g. U+20AC is the Euro sign. Color references in HTML, CSS and X Window can be expressed with six hexadecimal digits prefixed with #: white, for example, is represented #FFFFFF.
CSS allows 3-hexdigit abbreviations with one hexdigit per component: #FA3 abbreviates #FFAA33. Unix shells, AT&T assembly language and the C programming language use the prefix 0x for numeric constants represented in hex: 0x5A3. Character and string constants may express character codes in hexadecimal with the prefix \x followed by two hex digits:'\x1B' represents the Esc control character. To output an integer as hexadecimal with the printf function family, the format conversion code %X or %x is used. In MIME quoted-printable encoding, characters that cannot be represented as literal ASCII characters are represented by their codes as two hexadecimal digits prefixed by an equal to sign =, as in Espa=F1a to send "España". In Intel-derived assembly languages and Modula-2, hexadecimal is denoted with a suffixed H or h: FFh or 05A3H; some implementations require a leading zero when the first hexadecimal digit character is not a decimal digit, so one would write 0FFh instead of FFh Other assembly languages, Delphi, some versions of BASIC, GameMaker Language and Forth use $ as a prefix: $5A3.
Some assembly languages use the notation H'ABCD'. Fortran 95 uses Z'ABCD'. Ada and VHDL enclose hexadecimal numerals in based "numeric quotes": 16#5A3#. For bit vector constants VHDL uses the notation x"5A3". Verilog represents hexadecimal constants in the form 8'hFF, where 8 is the number of bits in the value and FF is the hexadecimal constant; 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: AA213FD51B3801043FBC... Common Lisp uses the prefixes # 16r. Setting the variables *read-base* and *print-base* to 16 can be 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, when the input or output base has been changed to 16. 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 ALGOL 68 uses the prefix 16r to denote hexadecimal numbers: 16r5a3. Binary and octal numbers can be specified similarly; the most common format for hexadecimal on IBM mainframes and midrange computers running the traditional OS's is X'5A3', is used in Assembler, PL/I, COBOL, JCL, scripts and other places. This format was common on