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Encyclopedia > IBM Personal Computer
IBM Personal Computer
Type Personal computer
Released August 12, 1981
Discontinued April 2, 1987
Processor Intel 8088 @ 4.77 MHz
Memory 16 kB ~ 640 kB
Operating system IBM BASIC / PC-DOS 1.0
CP/M-86
UCSD p-System

The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981. It was created by a team of engineers and designers under the direction of Don Estridge of the IBM Entry Systems Division in Boca Raton, Florida. IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC, XT, or AT internal design, facilitated by various manufacturers... Download high resolution version (1024x740, 91 KB) IBM PC 5150 with keyboard and green monochrome monitor (5151), running MS-DOS 5. ... is the 224th day of the year (225th in leap years) in the Gregorian calendar. ... Year 1981 (MCMLXXXI) was a common year starting on Thursday (link displays the 1981 Gregorian calendar). ... is the 92nd day of the year (93rd in leap years) in the Gregorian calendar. ... Year 1987 (MCMLXXXVII) was a common year starting on Thursday (link displays 1987 Gregorian calendar). ... A kilobyte (derived from the SI prefix kilo-, meaning 1,000) is a unit of information or computer storage equal to either 1,000 bytes or 1,024 bytes (210), depending on context. ... IBM PC-DOS was one of the three major operating systems that dominated the personal computer market from about 1985 to 1995. ... CP/M-86 was a version of the CP/M operating system that Digital Research made for the Intel 8086 and Intel 8088. ... The UCSD p-System or UCSD Pascal System was a portable highly machine independent operating system developed in 1978 by the Institute for Information Systems of the University of California, San Diego to provide all students with a common operating system that could run on any of the then available... IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC, XT, or AT internal design, facilitated by various manufacturers... In computing, a platform describes some sort of framework, either in hardware or software, which allows software to run. ... is the 224th day of the year (225th in leap years) in the Gregorian calendar. ... Year 1981 (MCMLXXXI) was a common year starting on Thursday (link displays the 1981 Gregorian calendar). ... Philip Donald Estridge (1937 - August 2, 1985), known as Don Estridge, led development of the original IBM Personal Computer (PC), and thus is known as father of the IBM PC. His decisions dramatically changed the computer industry, resulting in a vast increase in the number of personal computers sold and... For other uses, see IBM (disambiguation) and Big Blue. ... Nickname: Coordinates: , Country State County Palm Beach Founded 1925 Government  - Type Commission-Manager  - Mayor Steven L. Abrams Area  - City  29. ...


The term "personal computer" was common currency before 1981, and was used as early as 1972 to characterize Xerox PARC's Alto. However, because of the success of the IBM PC, what had been a generic term came to mean specifically a microcomputer compatible with IBM's specification. Bold text // Headline text Link title This article is about the computer research center. ... The Xerox Alto monitor has a portrait orientation. ... The Commodore 64 was one of the most popular microcomputers of its era, and is the best selling model of home computer of all time. ...

Contents

Concept

The original PC was an IBM attempt to get into the small computer market then dominated by the Commodore PET, Atari 8-bit family, Apple II and Tandy Corporation's TRS-80s, and various CP/M machines.[1] The PET (Personal Electronic Transactor) was a home-/personal computer produced by Commodore starting in the late 1970s. ... An Atari 800XL, one of the most popular machines in the series. ... The Apple II was one of the most popular personal computers of the 1980s. ... Tandy Corporation is the former name of the parent company of RadioShack Corporation, a Fort Worth, Texas-based company best known for its RadioShack electronics stores. ... This article does not cite any references or sources. ... CP/M is an operating system originally created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc. ...


Rather than going through the usual IBM design process, which had already failed to design an affordable microcomputer (the unsuccessful IBM 5100), a special team was assembled with authorization to bypass normal company restrictions and get something to market rapidly. This project was given the code name Project Chess. The IBM 5100 Portable Computer The IBM 5100 Portable Computer was a desktop computer introduced in September 1975, six years before the IBM PC. It was the evolution of a prototype called the SCAMP (Special Computer APL Machine Portable) that IBM demonstrated in 1973. ...


The team consisted of twelve people headed by Don Estridge and Chief Scientist Larry Potter. They developed the PC in about a year. To achieve this they first decided to build the machine with "off-the-shelf" parts from a variety of different original equipment manufacturers (OEMs) and countries. Previously IBM had developed their own components. Second, they decided on an open architecture so that other manufacturers could produce and sell peripheral components and compatible software. IBM also sold an IBM PC Technical Reference Manual which included a listing of the ROM BIOS source code.[2] Official IBM picture of Don Estridge, courtesy The History of Computing Project (www. ... Original equipment manufacturer, or OEM, is a term that refers to containment-based re-branding, namely where one company uses a component of another company within its product, or sells the product of another company under its own brand. ... A typical vision of a computer architecture as a series of abstraction layers: hardware, firmware, assembler, kernel, operating system and applications (see also Tanenbaum 79). ... Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. ... For other uses, see Bios. ... Source code (commonly just source or code) is any series of statements written in some human-readable computer programming language. ...


At the time, Don Estridge and his team considered using the IBM 801 processor and its operating system that had been developed at the IBM research laboratory in Yorktown Heights, New York (The 801 is an early RISC microprocessor designed by John Cocke and his team at Yorktown Heights.) The 801 was at least an order of magnitude more powerful than the Intel 8088, and the operating system many years more advanced than the DOS operating system from Microsoft, that was finally selected. Ruling out an in-house solution made the team’s job much easier and may have avoided a delay in the schedule, but the ultimate consequences of this decision for IBM were far-reaching. The 801 was a RISC microprocessor architecture designed by IBM in the 1970s, and used in various roles in IBM until the 1980s. ... Yorktown Heights is an unincorporated hamlet and census-designated place (CDP) located in the town of Yorktown in Westchester County, New York. ... Reduced Instruction Set Computer (RISC), is a microprocessor CPU design philosophy that favors a smaller and simpler set of instructions that all take about the same amount of time to execute. ... A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... The Intel 8088 is an Intel microprocessor based on the 8086, with 16-bit registers and an 8-bit external data bus. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ...


Other manufacturers soon reverse engineered the BIOS to produce their own non-infringing functional copies. Columbia Data Products introduced the first IBM-PC compatible computer in June 1982. In November 1982, Compaq Computer Corporation announced the Compaq Portable, the first portable IBM PC compatible. The first models were shipped in March 1983. Reverse engineering (RE) is the process of taking something (a device, an electrical component, a software program, etc. ... Columbia Data Products (CDP) introduced the MPC 1600 Multi Personal Computer in June 1982. ... Compaq Computer Corporation was founded in February 1982 by Rod Canion, Jim Harris and Bill Murto, three senior managers from semiconductor manufacturer Texas Instruments. ... The Compaq Portable was the first midget in the Compaq portable series to be brought out by Compaq Computer Corporation. ...


Once the IBM PC became a commercial success the PC came back under the usual IBM management control, with the result that competitors had little trouble taking the lead from them. (In this regard, IBM's tradition of "rationalizing" their product lines—deliberately restricting the performance of lower-priced models in order to prevent them from "cannibalizing" profits from higher-priced models—worked against them).


Third-party distribution

Sears Roebuck and Computerland executives were involved with the IBM team from the start. The IBMers - especially H.L. ('Sparky') Sparks, who was in charge of sales and marketing - relied on them for much of their knowledge of the marketplace. In turn, almost by default, they were to become the main outlets for the new product. Sears Roebuck would set up a handful of computer centers. Most important, more than 190 Computerland stores already existed. From IBM's point of view, this meant that there would be immediate widespread distribution across the US. In the event, Sears Roebuck failed to live up to expectations, when the new PC turned out to be selling to the office market rather than the home - where it had originally been targeted.


The use of outside organizations ('third parties' in IBM terminology) to sell IBM's products did not stop with the PC; for the whole of IBM's business had gradually evolved to the state where it was selling ever larger numbers of ever cheaper 'boxes'. The only way that IBM felt - at that time - it could, in general, handle the numbers of these new customers was by handing over the lower end of its business to 'retailers'; an approach that many other companies had successfully adopted in the past - from the producers of groceries (whose experience may not all have been totally relevant, though their experience of advertising to large numbers of end users might have been) to the manufacturers of cars (most of whose experiences, from handling their dealers to advertising on the large scale, might have been very relevant indeed). Certainly, by the end of the 1990s, more PCs were being sold worldwide than cars or even TVs.


Models

A release photo of the original IBM PC (ca. 1981).

The models of IBM's first-generation Personal Computer (PC) series have names: Image File history File links IBM_PC_5150_Image. ... Image File history File links IBM_PC_5150_Image. ...

The original PC had a version of Microsoft BASICIBM Cassette BASIC— in ROM. The CGA (Color Graphics Adapter) video card could use a standard television for display; the other option that was offered by IBM is a MDA (Monochrome Display Adapter) and a monochrome display model 5151. The standard storage device is cassette tape. A floppy disk drive is an optional extra; no factory-installed hard disk was available. It had only five expansion slots; maximum memory using IBM parts is 256 kilobytes, 64 kB on the main board and three 64 kB expansion cards. The processor is an Intel 8088 (early 1978 version, later were 1978/81/2 versions of intel chip, second-sourced AMDs were used after 1983) running at 4.77 MHz (4/3 the standard NTSC color burst frequency of 3.579545 MHz), which could be replaced with a NEC V20 for a slight increase in processing speed. An Intel 8087 co-processor could also be added for enhanced mathematical processing power. IBM sold it in configurations with 16 kB or 64 kB of RAM preinstalled using either nine or thirty-six 16 kBit DRAM chips. (As was common at the time, an extra bit is used for parity checking of memory.) The IBM 5161 Expansion Chassis was eventually released and allowed for more expansion boards to be installed as well as additional hard drives. The IBM Personal Computer XT, often shortened to the PC XT or simply XT, was IBMs successor to the original IBM PC. It was released as IBM product number 5160 on March 8, 1983, and was one of the first computers to come standard with a hard drive. ... The IBM Personal Computer/AT, more commonly known as the IBM AT and also sometimes called the PC AT or PC/AT, was IBMs second-generation PC, designed around the 6 MHz Intel 80286 microprocessor and released in 1984 as model number 5170. ... IBM PC Convertible The IBM Convertible was the follow-on to the IBM Portable, and was IBMs first attempt at a laptop computer. ... The IBM Portable was an early portable computer developed by IBM after the success of Compaqs suitcase-size portable machine (the Compaq Portable). ... A PCjr with the revised keyboard and a third-party floppy drive (attached to the top of the computer). ... Microsoft BASIC is the foundation product of the Microsoft company. ... IBM Cassette BASIC was a version of the Microsoft BASIC programming language licensed by IBM for the IBM PC. It was included in the BIOS ROM of the original IBM PC. Cassette BASIC provided the default user interface if there was no floppy disk drive installed, or if the boot... The 640×200 2 color mode with its default foreground color — Arachne Internet suite. ... Green screen driven by a Monochrome Display Adapter The Monochrome Display Adapter (MDA, also MDA card, Monochrome Display and Printer Adapter, MDPA) introduced in 1981 was IBMs standard video display card and computer display standard for the PC. The MDA did not have any graphics mode of any kind... Typical 60-minute Compact Cassette. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... Typical hard drives of the mid-1990s. ... The Intel 8088 is an Intel microprocessor based on the 8086, with 16-bit registers and an 8-bit external data bus. ... Advanced Micro Devices, Inc. ... Year 1983 (MCMLXXXIII) was a common year starting on Saturday (link displays the 1983 Gregorian calendar). ... MegaHertz (MHz) is the name given to one million (106) Hertz, a measure of frequency. ... The NEC V20 was a processor made by NEC that featured approximately 29,000 transistors. ... Intel C8087 Math Coprocessor The 8087 was the first math coprocessor designed by Intel and it was built to be paired with the ass] microprocessors. ... Different types of RAM. From top to bottom: DIP, SIPP, SIMM 30 pin, SIMM 72 pin, DIMM, RIMM RAM redirects here. ... Dram can mean several things: Dram (unit), an imperial unit of volume Dram, an imperial unit of weight or mass, see avoirdupois and apothecaries system Ottoman dram, a unit of weight, see dirhem Armenian dram, a monetary unit DRAM, a type of RAM Category: ... Look up Parity in Wiktionary, the free dictionary Parity is a concept of equality of status or functional equivalence. ...


The original PC proved too expensive for the home market, but was an unexpectedly large success with businesses. The "IBM Personal Computer XT" is an enhanced machine that was designed for business use. It has 8 expansion slots and a 10 megabyte hard disk. It can take 256 kB of memory on the main board (now that 64 Kbit DRAM has been introduced); later models are expandable to 640 kB. (The 384 kB of BIOS ROM + video RAM space fills the rest of the one megabyte address space of the 8088 CPU.) It was usually sold with a Monochrome Display Adapter (MDA) video card. Te processor is a 4.77 MHz Intel 8088 and the expansion bus 8-bit Industry Standard Architecture (ISA) with XT bus architecture. Green screen driven by a Monochrome Display Adapter The Monochrome Display Adapter (MDA, also MDA card, Monochrome Display and Printer Adapter, MDPA) introduced in 1981 was IBMs standard video display card and computer display standard for the PC. The MDA did not have any graphics mode of any kind... The Intel 8088 is an Intel microprocessor based on the 8086, with 16-bit registers and an 8-bit external data bus. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ... This article does not cite any references or sources. ... Industry Standard Architecture (in practice almost always shortened to ISA) is a computer bus standard for IBM compatibles. ...


The "IBM Personal Computer/AT", announced August 1984, uses an Intel 80286 processor, originally at 6 MHz. It has a 16-bit ISA bus and 20 MB hard drive. A faster model, running at 8 MHz, was introduced in 1986. IBM made some attempt at marketing it as a multi-user machine, but it sold mainly as a faster PC for power users. Early PC/ATs were plagued with reliability problems, in part because of some software and hardware incompatibilities, but mostly related to the internal 20 MB hard disk. While some people blamed IBM's hard disk controller card and others blamed the hard disk manufacturer Computer Memories Inc. (CMI), the IBM controller card worked fine with other drives, including CMI's 33-megabyte model. The problems introduced doubt about the computer and, for a while, even about the 286 architecture in general, but after IBM replaced the 20 MB CMI drives, the PC/AT proved reliable and became a lasting industry standard. AMD 80286 at 12 MHz. ... Typical hard drives of the mid-1990s. ... The disk controller (or hard disk controller) is the circuit which allows the CPU to communicate with a hard disk, floppy disk or other kind of disk drive. ... Computer Memories Inc. ...


All IBM personal computers are software compatible with each other in general, but not every program will work in every machine. Some programs are time sensitive to a particular speed class. Older programs will not take advantage of newer higher-resolution display standards. Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ...

The IBM PC range
Model name Model # Introduced CPU Features
PC 5150 Aug 1981 8088 Floppy disk system
XT 5160 Mar 1983 8088 First IBM PC with a hard disk
XT/370 5160/588 Oct 1983 8088 System/370 mainframe emulation
3270 PC 5271 Oct 1983 8088 With 3270 terminal emulation
PCjr 4860 Nov 1983 8088 Floppy-based home computer
PC Portable 5155 Feb 1984 8088 Floppy-based portable
AT 5170 Aug 1984 80286 Medium-speed hard disk
Convertible 5140 Apr 1986 8088 Microfloppy laptop portable
XT 286 5162 Sep 1986 80286 Slow hard disk, but zero wait state memory on the motherboard. This 6 MHz machine was actually faster than the 8 MHz ATs (when using planar memory) because of the zero wait states
IBM PC compatible specifications
CPU Clock
speed
(MHz)
CPU
bus
width (bits)
System
Bus
width (bits)
RAM
(mebibytes)
Floppy
disk drive
Hard drive
(megabytes)
Operating
system
8088 4.77–9.5 16 8 1[3] 5.25", 360 kB
3.5", 720 kB
3.5", 1.44 MB
10–40 PC-DOS
8086 6–12 16 20–60
80286 6–25 1–8[4] 5.25", 360 kB
5.25", 1.2 MB
20–300 PC-DOS, OS/2

IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... The IBM Personal Computer XT, often shortened to the PC XT or simply XT, was IBMs successor to the original IBM PC. It was released as IBM product number 5160 on March 8, 1983, and was one of the first computers to come standard with a hard drive. ... Typical hard drives of the mid-1990s. ... IBM logo The IBM System/370 (often: S/370) was a model range of IBM mainframes announced on June 30, 1970 as the successors to the System/360 family. ... SAS 8 on an IBM mainframe, seen here via one of its user interfaces, classic 3270 emulation. ... This article is about emulation in computer science. ... The IBM 3270 PC (model 5271), released in October 1983, was an IBM PC XT containing additional hardware which could emulate the behaviour of a 3270 terminal. ... Clemson Universitys Library Catalog The IBM 3270 is a class of terminals made by IBM (known as Display Devices) normally used to communicate with IBM mainframes. ... A PCjr with the revised keyboard and a third-party floppy drive (attached to the top of the computer). ... The IBM Portable was an early portable computer developed by IBM after the success of Compaqs suitcase-size portable machine (the Compaq Portable). ... The IBM Personal Computer/AT, more commonly known as the IBM AT and also sometimes called the PC AT or PC/AT, was IBMs second-generation PC, designed around the 6 MHz Intel 80286 microprocessor and released in 1984 as model number 5170. ... IBM PC Convertible The IBM Convertible was the follow-on to the IBM Portable, and was IBMs first attempt at a laptop computer. ... A wait state is a delay experienced by a computer processor when accessing external memory or another device that is slow to respond. ... BIT is an acronym for: Bannari amman Institute of Technology Bangalore Institute of Technology Beijing Institute of Technology Benzisothiazolinone Bilateral Investment Treaty Bhilai Institute of Technology - Durg Birla Institute of Technology - Mesra Battles in Time (Doctor Who magazine) BIT International College, formerly the Bohol Institute of Technology in Bohol, Philippines... MiB redirects here. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... Typical hard drives of the mid-1990s. ... ReBoot character, see Megabyte (ReBoot). ... An operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources. ... IBM PC-DOS was one of the three major operating systems that dominated the personal computer market from about 1985 to 1995. ... IBM PC-DOS was one of the three major operating systems that dominated the personal computer market from about 1985 to 1995. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Technology

Electronics

The main circuit board in an IBM PC is called the motherboard. This carries the CPU and memory, and has a bus with slots for expansion cards. The ABIT KT7, an ATX format motherboard A motherboard is a printed circuit board used in a personal computer. ... CPU redirects here. ... The terms storage (U.K.) or memory (U.S.) refer to the parts of a digital computer that retain physical state (data) for some interval of time, possibly even after electrical power to the computer is turned off. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ...


The bus used in the original PC became very popular, and was subsequently named ISA. It is in use to this day in computers for industrial use. Later, requirements for higher speed and more capacity forced the development of new versions. IBM introduced the MCA bus with the PS/2 line. The VESA Local Bus allowed for up to three, much faster 32-bit cards, and the EISA architecture was developed as a backward compatible standard including 32-bit card slots, but it only sold well in high-end server systems. The lower-cost and more general PCI bus was introduced in 1994 and has now become ubiquitous. This article does not cite any references or sources. ... This article or section does not adequately cite its references or sources. ... This article or section does not cite any references or sources. ... EISA means: Extended Industry Standard Architecture European Imaging and Sound Association (EISA Awards). ... 64-bit PCI expansion slots inside a Power Macintosh G4 The Peripheral Component Interconnect, or PCI Standard (in practice almost always shortened to PCI), specifies a computer bus for attaching peripheral devices to a computer motherboard. ... Year 1994 (MCMXCIV) The year 1994 was designated as the International Year of the Family and the International Year of the Sport and the Olympic Ideal by the United Nations. ...


The motherboard is connected by cables to internal storage devices such as hard disks, floppy disks and CD-ROM drives. These tend to be made in standard sizes, such as 3.5" (90 mm) and 5.25" (133.4 mm) widths, with standard fixing holes. The case also contains a standard power supply unit (PSU) which is either an AT or ATX standard size. Typical hard drives of the mid-1990s. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... The CD-ROM (an abbreviation for Compact Disc Read-Only Memory (ROM)) is a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. ... An electronic power supply, often referred to somewhat incorrectly as an AC adaptor, is an electronic device that produces direct current of a particular voltage and current from a source of electricity such as a battery or wall-socket power. ...


Intel 8086 and 8088-based PCs require expanded memory (EMS) boards to work with more than one megabyte of memory. The original IBM PC AT used an Intel 80286 processor which can access up to 16 megabytes of memory (though standard DOS applications cannot use more than one megabyte without using additional APIs.) Intel 80286-based computers running under OS/2 can work with the maximum memory. Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... The Intel 8088 is an Intel microprocessor based on the 8086, with 16-bit registers and an 8-bit external data bus. ... Expanded Memory was a trick invented around 1984 that provided more memory to byte-hungry, business-oriented MS-DOS programs. ... ReBoot character, see Megabyte (ReBoot). ... AMD 80286 at 12 MHz. ... This article is about the family of closely related operating systems for the IBM PC compatible platform. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


Keyboard

The original 1981 IBM PC's keyboard at the time was an extremely reliable and high quality keyboard originally developed in North Carolina for another $10,000 IBM computer system that had been canceled. Each key was rated to be reliable to over 100 million keystrokes. Compared to the keyboards of other small computers at the time, the IBM PC keyboard was far superior and played a significant role in establishing a high quality impression. Byte magazine in the fall of 1981 went so far as to state that the keyboard was 50 percent of the reason to buy an IBM PC. The importance of the keyboard was definitely established when the IBM PCjr flopped, in very large part for having a much different and mediocre Chiclet keyboard that made a poor impression on customers. Oddly enough, the same thing almost happened to the IBM PC when in early 1981 management seriously considered substituting a cheaper but lower quality keyboard. This mistake was narrowly avoided by the advice of one of the original development engineers. December 1975 issue of Byte (Vol 1. ... A PCjr with the revised keyboard and a third-party floppy drive (attached to the top of the computer). ... A chiclet keyboard is slang for a computer keyboard built with an array of small, flat rectangular or lozenge-shaped rubber or plastic keys that look like erasers or pieces of chewing gum. ...


However, the original 1981 IBM PC's keyboard was severely criticized by typists for its non-standard placement of the return and left shift keys. In 1984, IBM corrected this on its AT keyboard, but shortened the backspace key, making it harder to reach. In 1987, it introduced the enhanced keyboard, which relocated all the function keys and the Ctrl keys. The Esc key was also relocated to the opposite side of the keyboard. A 104-key PC US English QWERTY keyboard layout The Dvorak Simplified Keyboard layout A standard Hebrew keyboard showing both Hebrew and QWERTY. A computer keyboard is a peripheral partially modelled after the typewriter keyboard. ... This article is about the year. ... The enhanced keyboard was first made by IBM; it has over 101 keys and is now the standard keyboard for PCs. ...


Another criticism of the original keyboard was the relatively loud "clack" sound each key made when pressed. Since typewriter users were accustomed to keeping their eyes on the hardcopy they were typing from and had come to rely on the sound that was made as each character was typed onto the paper to ensure that they had pressed the key hard enough (and only once), the PC keyboard "clack" feature was intended to provide that same reassurance. However, it proved to be very noisy and annoying, especially if many PCs were in use in the same room, and later keyboards were significantly quieter.


An "IBM PC compatible" may have a keyboard that does not recognize every key combination a true IBM PC does, such as shifted cursor keys. In addition, the "compatible" vendors sometimes used proprietary keyboard interfaces, preventing the keyboard from being replaced.


Although the PC/XT and AT used the same style of keyboard connector, the low-level protocol for reading the keyboard was different between these two series. An AT keyboard could not be used in an XT, nor the reverse. Third-party keyboard manufacturers provided a switch to select either AT-style or XT-style protocol for the keyboard.

See also: Keyboard layout

A standard Hebrew keyboard showing both Hebrew and English (QWERTY) letters. ...

Serial port addresses and interrupts

COM Port IRQ Base Port Address
COM1 IRQ4 3F8H
COM2 IRQ3 2F8H
COM3 IRQ4 3E8H
COM4 IRQ3 2E8H

Only COM1: and COM2: addresses were defined by the original PC. Attempts to share IRQ 3 and IRQ4 to use additional ports require special measures in hardware and software, since shared IRQs were not defined in the original PC design.


Character set

The original IBM PC used the 7-bit ASCII alphabet as its basis, but extended it to 8 bits with nonstandard character codes. This character set was not suitable for some international applications, and soon a veritable cottage industry emerged providing variants of the original character set in various national variants. In IBM tradition, these variants were called code pages. These codings are now obsolete, having been replaced by more systematic and standardized forms of character coding, such as ISO 8859-1, Windows-1251 and Unicode. The original character set is known as Code page 437. Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ... Code page is the traditional IBM term used for a specific character encoding table: a mapping in which a sequence of bits, usually a single octet representing integer values 0 through 255, is associated with a specific character. ... ISO 8859-1, more formally cited as ISO/IEC 8859-1 or less formally as Latin-1, is part 1 of ISO/IEC 8859, a standard character encoding originally developed by ISO, but later jointly maintained by ISO and IEC. The standard, when supplemented with additional character assignments, is the... Windows-1251 is an 8-bit character encoding, designed to cover languages that use the Cyrillic alphabet such as Russian and other languages. ... The Unicode Standard, Version 5. ... IBM PC or MS-DOS code page 437, often abbreviated CP437 and also known as DOS-US or OEM-US, is the original character set of the IBM PC, circa 1981. ...


Storage media

5 1/4 inch Diskette Drive with a partially inserted double-density diskette running on DOS 1.1.

Originally, the only storage medium for the original IBM PC model 5150 was a port for connection to a cassette drive. This was not the sort of unit expected in such an expensive computer and it was seldom used; few (if any) IBM PCs left the factory without a floppy disk drive installed. The 1981 PC had one or two 160 kilobyte 5¼ inch single-sided double-density floppy disk drives (180 kilobyte in later MS-DOS versions).[5] XTs generally had one double-sided 360 kB drive (next to the hard disk). Image File history File links Metadata Size of this preview: 750 × 600 pixelsFull resolution (2000 × 1600 pixel, file size: 398 KB, MIME type: image/jpeg) IBM PC 5 1/4 inch Diskette Drive shown with DOS 1. ... Image File history File links Metadata Size of this preview: 750 × 600 pixelsFull resolution (2000 × 1600 pixel, file size: 398 KB, MIME type: image/jpeg) IBM PC 5 1/4 inch Diskette Drive shown with DOS 1. ... The Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply tape, is a magnetic tape sound recording format. ... A kilobyte (derived from the SI prefix kilo-, meaning 1,000) is a unit of information or computer storage equal to either 1,000 bytes or 1,024 bytes (210), depending on context. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... Typical hard drives of the mid-1990s. ...


The first IBM PC that included a fixed, non-removable, hard disk was the XT. Hard disks for IBM compatibles soon became available with very large storage capacities. If a hard disk was added that was not compatible with the existing disk controller, a new controller board had to be plugged in; some disks were integrated with their controller in a single expansion board, commonly called a "Hard Card". The disk controller (or hard disk controller) is the circuit which allows the CPU to communicate with a hard disk, floppy disk or other kind of disk drive. ...


In 1984, IBM introduced the 1.2 megabyte dual sided floppy disk along with its AT model. Although often used as backup storage, the high density floppy was not often used by software manufacturers for interchangeability. In 1986, IBM began to use the 720 kB double density 3.5" microfloppy disk on its Convertible laptop computer. It introduced the 1.44 MB high density version with the PS/2 line. These disk drives could be added to existing older model PCs. In 1988 IBM introduced a drive for 2.88 MB "DSED" diskettes in its top-of-the-line PS/2 models; it was an instant failure and is all but forgotten today (but survives as a possible "size" choice in disk-formatting utilities). Double Density usually refers to a physical format in a magnetic storage system that uses twice as many bits per length unit as the basic format. ... High density for data storage like diskette,cd or dvd refers to the amount of information they manage. ... Formatting a hard drive using MS-DOS This article needs cleanup. ...


Original software

All IBM PCs include a relatively small piece of software stored in ROM. The original IBM PC 40 KB ROM included 8 KB for power-on self-test (POST) and basic input/output system (BIOS) functions plus 32 KB BASIC in ROM (Cassette BASIC). The ROM BASIC interpreter was the default user interface if no DOS boot disk was present. BASICA was distributed on floppy disk and provided a way to run the ROM BASIC under PC-DOS control. Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. ... Power-off self-test (POST) is the common term for a computers, routers or printers pre-boot sequence. ... For other uses, see Bios. ... BASIC (Beginners All-purpose Symbolic Instruction Code) is a family of high-level programming languages. ... IBM Cassette BASIC was a version of the Microsoft BASIC programming language licensed by IBM for the IBM PC. It was included in the BIOS ROM of the original IBM PC. Cassette BASIC provided the default user interface if there was no floppy disk drive installed, or if the boot... This article is about the family of closely related operating systems for the IBM PC compatible platform. ... A boot disk is a removable media, normally read-only, that can boot an operating system or utility. ... Microsoft BASICA (short for Advanced BASIC) is a simple disk-based BASIC interpreter written by Microsoft for PC-DOS. BASICA allows use of the ROM-resident BASIC on the PC while DOS is loaded (the ROM BASIC itself runs when nothing is loaded when booting) and adds functionality such as... IBM PC-DOS was one of the three major operating systems that dominated the personal computer market from about 1985 to 1995. ...


In addition to PC-DOS, buyers could choose either CP/M-86 or UCSD p-System as operating systems. Due to their higher prices, they never became very popular and PC-DOS or MS-DOS came to be the dominant operating system. IBM PC-DOS was one of the three major operating systems that dominated the personal computer market from about 1985 to 1995. ... CP/M-86 was a version of the CP/M operating system that Digital Research made for the Intel 8086 and Intel 8088. ... The UCSD p-System or UCSD Pascal System was a portable highly machine independent operating system developed in 1978 by the Institute for Information Systems of the University of California, San Diego to provide all students with a common operating system that could run on any of the then available...


Longevity

While the IBM PC technology is largely obsolete by today's standards, many are still in service. As of June 2006, IBM PC and XT models are still in use at the majority of U.S. National Weather Service upper-air observing sites. The computers are used to process data as it is returned from the ascending radiosonde, attached to a weather balloon. They are being phased out over a several year period, to be replaced by the Radiosonde Replacement System. The National Weather Service (NWS) is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration (NOAA) of the United States government. ... radiosonde with measuring instruments A radiosonde (Sonde is German for probe) is a unit for use in weather balloons that measures various atmospheric parameters and transmits them to a fixed receiver. ... Rawinsonde weather balloon just after launch. ...


See also

This article is about the machine. ... Conventional memory is the first 640 kibibytes of an IBM PCs memory. ... For other uses, see IBM (disambiguation) and Big Blue. ... IBM token ring refers to IBMs implementation of token ring technology for linking personal computers in a local area network (LAN). ... The IBM PS/1 personal computer was IBMs return to the home market in 1990, five years after the IBM PCjr. ... IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC, XT, or AT internal design, facilitated by various manufacturers... The following is a list of products from the International Business Machines (IBM) Corporation and its predecessor corporations, beginning in the 1890s, and spanning punched card machinery, time clocks, and typewriters, via mainframe computers and minicomputers, to microprocessors, PCs, laptop PCs, and more. ... IBM ThinkPad R51 ThinkPad is the brand name for a range of portable laptop and notebook computers originally designed and sold by IBM. Since early 2005 the ThinkPad range has been manufactured and marketed by Lenovo, which purchased the IBM PC division. ... ThinkCentre is a line of desktop computers manufactured by IBM, the successor to the NetVista and Aptiva lines. ... Base address is also called I/O port, I/O address, I/O port address and base port. ... The IBM 5120 Computing System (sometimes referred to as the IBM 5110 Model 3) was the desktop version of the IBM 5110 Portable Computer which featured two built-in 8 inch 1. ... The IBM Personal Computer XT, often shortened to the PC XT or simply XT, was IBMs successor to the original IBM PC. It was released as IBM product number 5160 on March 8, 1983, and was one of the first computers to come standard with a hard drive. ... The IBM Portable Personal Computer 5155 model 68 was an early portable computer developed by IBM after the success of Compaqs suitcase-size portable machine (the Compaq Portable). ... A PCjr with the revised keyboard and a third-party floppy drive (attached to the top of the computer). ...

Notes

  1. ^ "Total share: 30 years of personal computer market share figures", Jeremy Reimer Dec.14, 2005 http://arstechnica.com/articles/culture/total-share.ars/4
  2. ^ Charlie Anderson (2003-11-13). The Virtual PC Museum. Charlie Anderson. Retrieved on 2006-12-16.. Personal website with an image of the technical manual. "The official documentation came in cool three-ring binders, complete with slip covers. Completely typeset.... This book wasn't free, either—I think it cost $60. Supposedly, no Compaq BIOS programmer ever saw one of these. Yeah, right." Jargon File 3.0.0—TechRef. Jargon File, TechRef: /tek'ref/ [MS-DOS] n. The original "IBM PC Technical Reference Manual", including the BIOS listing and complete schematics for the PC. The only PC documentation in the issue package that's considered serious by real hackers."
  3. ^ Under DOS, RAM is expanded beyond 1 MB with EMS memory boards
  4. ^ Under DOS, RAM is expanded beyond 1 MB with normal "extended" memory and a memory management program
  5. ^ IBM (July 1982). Technical Reference: Personal Computer Hardware Reference Library, Revised Edition, IBM Corp., page 2-93. 6025008.  The drives are soft sectored, single or double sided, with 40 tracks per side. They are Modified Frequency Modulation (MFM) coded in 512 byte sectors, giving a formatted capacity of 163,840 bytes per drive for single sided and 327,680 bytes per drive for double sided.

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 350th day of the year (351st in leap years) in the Gregorian calendar. ... Expanded Memory was a trick invented around 1984 that provided more memory to byte-hungry, business-oriented MS-DOS programs. ... Extended memory refers to memory above the first megabyte of address space in an IBM PC with an 80286 or later processor. ...

References

  • Norton, Peter (1986). Inside the IBM PC. Revised and enlarged. New York. Brady. ISBN 0-89303-583-1.
  • August 12, 1981 press release announcing the IBM PC (PDF format).
  • Mueller, Scott (1992) Upgrading and Repairing PCs, Second Edition, Que Books, ISBN 0-88022-856-3
  • Chposky, James; Ted Leonsis (1988). Blue Magic - The People, Power and Politics Behind the IBM Personal Computer. Facts On File. ISBN 0-8160-1391-8. 
  • This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.

is the 224th day of the year (225th in leap years) in the Gregorian calendar. ... Year 1981 (MCMLXXXI) was a common year starting on Thursday (link displays the 1981 Gregorian calendar). ... PDF is an abbreviation with several meanings: Portable Document Format Post-doctoral fellowship Probability density function There also is an electronic design automation company named PDF Solutions. ... This article does not cite any references or sources. ... “GFDL” redirects here. ...

External links

IBM PC Series
IBM 5120     IBM Personal Computer XT IBM Portable Personal Computer IBM PCjr
 

  Results from FactBites:
 
IBM 5155 portable computer (600 words)
The IBM Portable Personal Computer 5155 Model 68 consists of a lightweight case with a carrying handle containing a built-in.
The system board is the same as that of the IBM Personal Computer XT with 256Kb of memory that is expandable to 512Kb using the memory expansion option.
The 5155 was IBM's response to the Compaq Portable computer, which was released one year prior, costs $700 less, but has the same CPU and runs just as fast.
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