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Bit-paired Keyboard
A bit-paired keyboard is a keyboard where the layout of shifted keys corresponds to columns in the ASCII (1963) table, archetypally the Teletype Model 33 (1963) keyboard. This was later contrasted with a typewriter-paired keyboard, where the layout of shifted keys corresponds to ''electric'' typewriter layouts, notably the IBM Selectric (1961). The difference is most visible in the digits row (top row): compared with mechanical typewriters, bit-paired keyboards remove the _ character from 6 and shift the remaining &*() from 7890 to 6789, while typewriter-paired keyboards replace 3 characters: from " to @ from _ to ^ and from ' to *. An important subtlety is that ASCII was based on mechanical typewriters, but electric typewriters became popular during the same period that ASCII was adopted, and made their own changes to layout. Thus differences between bit-paired and (electric) typewriter-paired keyboards are due to the differences of both of these from earlier mechanical ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary-coded Decimal
In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for a sign or other indications (e.g. error or overflow). In byte-oriented systems (i.e. most modern computers), the term ''unpacked'' BCD usually implies a full byte for each digit (often including a sign), whereas ''packed'' BCD typically encodes two digits within a single byte by taking advantage of the fact that four bits are enough to represent the range 0 to 9. The precise four-bit encoding, however, may vary for technical reasons (e.g. Excess-3). The ten states representing a BCD digit are sometimes called '' tetrades'' (the nibble typically needed to hold them is also known as a tetrade) while the unused, don't care-states are named ''pseudo-tetrad(e)s'', ''pseudo-decimals'', or ''pseudo-decimal digits''. BCD's main virtue, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Personal Computer
A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as Word processor, word processing, web browser, internet browsing, email, multimedia playback, and PC game, gaming. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or technician. Unlike large, costly minicomputers and mainframes, time-sharing by many people at the same time is not used with personal computers. The term home computer has also been used, primarily in the late 1970s and 1980s. The advent of personal computers and the concurrent Digital Revolution have significantly affected the lives of people. Institutional or corporate computer owners in the 1960s had to write their own programs to do any useful work with computers. While personal computer users may develop their applications, usually these systems run commercial software, free-of-charge software ("freeware"), which i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Model M
Model M keyboards are a group of computer keyboards designed and manufactured by IBM starting in 1985, and later by Lexmark International, Maxi Switch, and Unicomp. The keyboard's different variations have their own distinct characteristics, with the vast majority having a buckling-spring key design and uniform profile, swappable keycaps. Model M keyboards are notable among computer enthusiasts and frequent typists due to their durability, typing-feel consistency, and their tactile and auditory feedback. The popularity of the IBM PC and its successors made the Model M's design influential: Almost all later general-purpose computer keyboards mimicked its key layout and other aspects of its ergonomics. The layout was standardized by ISO in 1994 and ANSI in 1998, with minor additions—most notably the Windows key and Menu key. The Model M is regarded as a classic and durable piece of hardware. Although the computers and computer peripherals produced concurrently with them ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM PC
The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the List of IBM Personal Computer models, IBM PC model line and the basis for the IBM PC compatible ''de facto'' standard. Released on August 12, 1981, it was created by a team of engineers and designers at IBM, International Business Machines (IBM), directed by William C. Lowe and Philip Don Estridge in Boca Raton, Florida. Powered by an x86-architecture Intel 8088 processor, the machine was based on open architecture and third-party peripherals. Over time, expansion cards and software technology increased to support it. The PC had influence of the IBM PC on the personal computer market, a substantial influence on the personal computer market; the specifications of the IBM PC became one of the most popular computer design standards in the world. The only significant competition it faced from a non-compatible platform throughout the 1980s was from Apple Inc., Apple's Maci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VT52
The VT50 is a CRT-based computer terminal that was introduced by Digital Equipment Corporation (DEC) in July 1974. It provided a display with 12 rows and 80 columns of upper-case text, and used an expanded set of control characters and forward-only scrolling based on the earlier VT05. DEC documentation of the era refers to the terminals as the DECscope, a name that was otherwise almost never seen. The VT50 was sold only for a short period before it was replaced by the VT52 in September 1975. The VT52 provided a screen of 24 rows and 80 columns of text and supported all 95 ASCII characters as well as 32 graphics characters, bi-directional scrolling, and an expanded control character system. DEC produced a series of upgraded VT52s with additional hardware for various uses. The VT52 family was followed by the much more sophisticated VT100 in 1978. Description These terminals supported asynchronous communication at baud rates up to 9600 bits per second and did not require ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Equipment Corporation
Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until he was forced to resign in 1992, after the company had gone into precipitous decline. The company produced many different product lines over its history. It is best known for the work in the minicomputer market starting in the early 1960s. The company produced a series of machines known as the Programmed Data Processor, PDP line, with the PDP-8 and PDP-11 being among the most successful minis in history. Their success was only surpassed by another DEC product, the late-1970s VAX "supermini" systems that were designed to replace the PDP-11. Although a number of competitors had successfully competed with Digital through the 1970s, the VAX cemented the company's place as a leading vendor in the computer space. As microcomputers improved in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apple II
Apple II ("apple Roman numerals, two", stylized as Apple ][) is a series of microcomputers manufactured by Apple Computer, Inc. from 1977 to 1993. The Apple II (original), original Apple II model, which gave the series its name, was designed by Steve Wozniak and was first sold on June 10, 1977. Its success led to it being followed by the Apple II Plus, Apple IIe, Apple IIc, and Apple IIc Plus, with the 1983 IIe being the most popular. The name is trademarked with square brackets as Apple ][, then, beginning with the IIe, as Apple //. The Apple II was a major advancement over its predecessor, the Apple I, in terms of ease of use, features, and expandability. It became one of several recognizable and successful computers throughout the 1980s, although this was mainly limited to the US. It was aggressively marketed through volume discounts and manufacturing arrangements to educational institutions, which made it the first computer in widespread use in American secondary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP 2640
The HP 2640A and other HP 264X models were block-mode "smart" and intelligent ASCII standard serial terminals produced by Hewlett-Packard using the Intel 8008 and 8080 microprocessors. History The HP 2640A was introduced in November 1974 at a list price of US$3000. Based on the Intel 8008 CPU, it had 8 KB of ROM firmware and came standard with 1 KB of RAM, expandable up to 8 KB (two 4 KB semiconductor RAM cards). In September 1975 Hewlett-Packard introduced the HP 2644A, which was an HP 2640A with mass storage (two mini-tape cartridges, 110 KB each), for US$5000. HP followed up in 1976 with the 2640B, an updated, cost-reduced version of the 2640A with a list price of US$2600, along with three international versions: the Cyrillic-oriented 2640C, the Swedish/Finnish-oriented 2640S, and the Danish/Norwegian-oriented 2640N. All of these early members of the 2640 series had the relatively slow 8008 CPU running at 700 kHz, and they were thus limited to speeds of 2400 baud. The 2640A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecma International
Ecma International () is a Nonprofit organization, nonprofit standards organization for information and communication systems. It acquired its current name in 1994, when the European Computer Manufacturers Association (ECMA) changed its name to reflect the organization's global reach and activities. As a consequence, the name is acronym#Pseudo-acronyms and orphan initialisms, no longer considered an acronym and no longer uses full capitalization. The organization was founded in 1961 to standardize computer systems in Europe. Membership is open to large and small companies worldwide that produce, market, or develop computer or communication systems, and have interest and experience in the areas addressed by the group's technical bodies. It is located in Geneva. Aims Ecma aims to develop Standardization, standards and Technical_report, technical reports to facilitate and standardize the use of information communication technology and consumer electronics; encourage the correct u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Standards Association
The American National Standards Institute (ANSI ) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international standards so that American products can be used worldwide. ANSI accredits standards that are developed by representatives of other standards organizations, government agencies, consumer groups, companies, and others. These standards ensure that the characteristics and performance of products are consistent, that people use the same definitions and terms, and that products are tested the same way. ANSI also accredits organizations that carry out product or personnel certification in accordance with requirements defined in international standards. The organization's headquarters are in Washington, D.C. ANSI's operations office is located in New York City. The ANSI annual operating b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromechanical
Electromechanics combine processes and procedures drawn from electrical engineering and mechanical engineering. Electromechanics focus on the interaction of electrical and mechanical systems as a whole and how the two systems interact with each other. This process is especially prominent in systems such as those of DC or AC rotating electrical machines which can be designed and operated to generate power from a mechanical process ( generator) or used to power a mechanical effect ( motor). Electrical engineering in this context also encompasses electronics engineering. Electromechanical devices are ones which have both electrical and mechanical processes. Strictly speaking, a manually operated switch is an electromechanical component due to the mechanical movement causing an electrical output. Though this is true, the term is usually understood to refer to devices which involve an electrical signal to create mechanical movement, or vice versa mechanical movement to create an ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
