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DECwriter
The DECwriter series was a family of computer terminals from Digital Equipment Corporation (DEC). They were typically used in a fashion similar to a teletype, with a computer output being printed to paper and the user inputting information on the keyboard. In contrast to teletypes, the DECwriters were based on dot matrix printer technology, one of the first examples of such a system to be introduced. Versions lacking a keyboard were also available for use as computer printers, which eventually became the only models as Block-oriented terminal, smart terminals became the main way to interact with mainframes and minicomputers in the 1980s. There were four series of machines, starting with the original DECwriter in 1970, the DECwriter II in 1974, DECwriter III in 1978, and the final DECwriter IV in 1982. The first three were physically similar, large machines mounted on a stand normally positioned above a box of fanfold paper. They differed primarily in speed and the selection of com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASCII
ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control characters a total of 128 code points. The set of available punctuation had significant impact on the syntax of computer languages and text markup. ASCII hugely influenced the design of character sets used by modern computers; for example, the first 128 code points of Unicode are the same as ASCII. ASCII encodes each code-point as a value from 0 to 127 storable as a seven-bit integer. Ninety-five code-points are printable, including digits ''0'' to ''9'', lowercase letters ''a'' to ''z'', uppercase letters ''A'' to ''Z'', and commonly used punctuation symbols. For example, the letter is represented as 105 (decimal). Also, ASCII specifies 33 non-printing control codes which originated with ; most of which are now obsolete. The control cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control Character
In computing and telecommunications, a control character or non-printing character (NPC) is a code point in a character encoding, character set that does not represent a written Character (computing), character or symbol. They are used as in-band signaling to cause effects other than the addition of a symbol to the text. All other characters are mainly ''graphic characters'', also known as ''printing characters'' (or ''printable characters''), except perhaps for "space (punctuation), space" characters. In the ASCII standard there are 33 control characters, such as code 7, , which rings a terminal bell. History Prosigns for Morse code, Procedural signs in Morse code are a form of control character. A form of control characters were introduced in the 1870 Baudot code: NUL and DEL. The 1901 Murray code added the carriage return (CR) and line feed (LF), and other versions of the Baudot code included other control characters. The bell character (BEL), which rang a bell to alert op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Case
Letter case is the distinction between the letters that are in larger uppercase or capitals (more formally ''majuscule'') and smaller lowercase (more formally '' minuscule'') in the written representation of certain languages. The writing systems that distinguish between the upper- and lowercase have two parallel sets of letters: each in the majuscule set has a counterpart in the minuscule set. Some counterpart letters have the same shape, and differ only in size (e.g. ), but for others the shapes are different (e.g., ). The two case variants are alternative representations of the same letter: they have the same name and pronunciation and are typically treated identically when sorting in alphabetical order. Letter case is generally applied in a mixed-case fashion, with both upper and lowercase letters appearing in a given piece of text for legibility. The choice of case is often denoted by the grammar of a language or by the conventions of a particular discipline. In ortho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Device Driver
In the context of an operating system, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details about the hardware being used. A driver communicates with the device through the computer bus or communications subsystem to which the hardware connects. When a calling program invokes a routine in the driver, the driver issues commands to the device (drives it). Once the device sends data back to the driver, the driver may invoke routines in the original calling program. Drivers are hardware dependent and operating-system-specific. They usually provide the interrupt handling required for any necessary asynchronous time-dependent hardware interface. Purpose The main purpose of device drivers is to provide abstraction b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Buffer
In computer science, a data buffer (or just buffer) is a region of memory used to store data temporarily while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device (such as a microphone) or just before it is sent to an output device (such as speakers); however, a buffer may be used when data is moved between processes within a computer, comparable to buffers in telecommunication. Buffers can be implemented in a fixed memory location in hardware or by using a virtual data buffer in software that points at a location in the physical memory. In all cases, the data stored in a data buffer is stored on a physical storage medium. The majority of buffers are implemented in software, which typically use RAM to store temporary data because of its much faster access time when compared with hard disk drives. Buffers are typically used when there is a difference between the rate at which data is received and the rate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDP 11-34, By The U
PDP may refer to: Computing and technology * Packet Data Protocol in wireless GPRS/HSDPA networks * Parallel distributed processing in connectionism * Plasma display panel * Policy Decision Point in the Common Open Policy Service * Portable DVD player * Power-delay product, the product of power consumption times the input–output delay * Power delay profile, signal intensity as a function of time delay * Primary Data Point in the RRDtool * Programmed Data Processor, Digital Equipment Corporation (DEC) minicomputers ** PDP-1, 1959 ** PDP-4, 1962 ** PDP-5, 1963 ** PDP-6, 1963 ** PDP-7, 1964 ** PDP-8, 1965 ** PDP-9, 1966 ** PDP-10, mainframe computer 1966-1983 ** PDP-11, 16-bit minicomputers 1970-1997 ** PDP-12, 1969 ** PDP-14, industrial controller, 1969 ** PDP-15, 1970 ** PDP-16, industrial controller, 1971 * Project Detail Page on Microsoft Project Server * XACML PDP (policy decision point) * Product Detail Page, a page showing the detail of one product on an e-commerce website ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
De Facto Standard
A ''de facto'' standard is a custom or convention that is commonly used even though its use is not required. is a Latin phrase (literally " of fact"), here meaning "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established". A ''de facto'' standard contrasts an international standard which is defined by an organization such as International Standards Organization, or a standard required by law (also known as ''de jure'' standards). Joint technical committee on information technology (ISO/IEC JTC1) developed a procedure in order for de facto standards to be processed through the formal standardization system to be transformed into international standards from ISO and IEC. In social sciences a voluntary standard that is also a ''de facto'' standard is a typical solution to a coordination problem. The choice of a ''de facto'' standard tends to be stable in situations in which all parties can realize mutual gains, but only by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centronics Port
IEEE 1284, also known as the Centronics port, is a standard that defines bi-directional parallel communications between computers and other devices. It was originally developed in the 1970s by Centronics before its IEEE standardization. History In the 1970s, Centronics developed the now-familiar printer parallel port that soon became a ''de facto'' standard. Centronics had introduced the first successful low-cost seven-wire print head, which used a series of solenoids to pull the individual metal pins to strike a ribbon and the paper. A dot matrix print head consists of a series of metal pins arranged in a vertical row. Each pin is attached to some sort of actuator, a solenoid in the case of Centronics, which can pull the pin forward to strike a ribbon and the paper. The entire print head is moved horizontally in order to print a line of text, striking the paper several times to produce a matrix for each character. Character sets on early printers normally used 7 by 5 "p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RS-232
In telecommunications, RS-232 or Recommended Standard 232 is a standard introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such as a computer terminal or PC, and a ''DCE'' ('' data circuit-terminating equipment'' or '' data communication equipment''), such as a modem. The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pinout of connectors. The current version of the standard is ''TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange'', issued in 1997. The RS-232 standard had been commonly used with serial ports and serial cables. It is still widely used in industrial communication devices. A serial port complying with the RS-232 standard was once a standard feature of many types of computers. Personal computers used them ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ADM-3A
The ADM-3A is an early influential video display terminal, introduced in 1976. It was manufactured by Lear Siegler and has a 12-inch screen displaying 12 or 24 lines of 80 characters. It set a new industry low single unit price of $995. Its "dumb terminal" nickname came from some of the original trade publication advertisements. It quickly became commercially successful because of the rapid increase of computer communications speeds, and because of new minicomputer and microcomputer systems released to the market which required inexpensive operator consoles. History Lear Siegler, Inc. (LSI) manufactured its first video display terminal in 1972 – the 7700A. In 1973, LSI hired a new head of engineering, Jim Placak. He and his team created the ADM-1 later that year. It set a new pricing low in the industry at $1,500. Its lower cost was primarily due to a unique single printed circuit board design. In early 1973 the LSI division in Anaheim, California that manufactured th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fill Characters
In computer terminology, a fill character is a character transmitted solely for the purpose of consuming time. It does this by filling a timeslot on a data transmission line which would otherwise be forced to be idle (empty). In this way, fill characters provide a simple way of timing required idle times. Fill characters are usually used in response to some real-world limitation. For example, mechanical computer printers such as the earliest dot matrix printers may have been able to print 30 characters per second, but when a "carriage return" character was received and the printhead began returning to the left margin, there was a noticeable delay before the printing of the next line could begin. Unlike modern printers, these early printers contained essentially no buffering, nor did they do any handshaking, so there would be no place to store the characters which would be received while the printhead was in the process of returning to the left margin, nor any way to tell the send ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
