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To comply with Wikipedia\'s quality standards, this article may need to be rewritten. Reason: Very large history section was moved to separate article. Please help improve this article. The discussion page may contain suggestions. |
A stylised illustration of a personal computer
A personal computer (PC) is a computer whose original sales price, size, and capabilities make it useful for individuals, intended to be operated directly by an end user, with no intervening computer operator.
A PC may be a home computer, or may be found in an office, often connected to a local area network. The distinguishing characteristics are that the computer is primarily used, interactively, by one person at a time. This is opposite to the batch processing or time-sharing models which allowed large expensive systems to be used by many people, usually at the same time, or large data processing systems which required a full-time staff to operate efficiently.
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The capabilities of the PC have changed greatly since the introduction of electronic computers. By the early 1970s, people in academic or research institutions had the opportunity for single-person use of a computer system in interactive mode for extended durations, although these systems would still have been too expensive to be owned by a single person. The introduction of the microprocessor, a single chip with all the circuitry that formerly occupied large cabinets, led to the proliferation of personal computers after about 1975. Early personal computers generally called microcomputers, sold often in kit form and in limited volumes, and were of interest mostly to hobbyists and technicians. By the late 1970s, mass-market pre-assembled computers allowed a wider range of people to use computers, focusing more on software applications and less on development of the processor hardware. Throughout the 1970s and 1980s, home computers were developed for household use, offering personal productivity, programming and games. Somewhat larger and more expensive systems (although still low-cost compared with minicomputers and mainframes) were aimed for office and small business use. Workstations are characterized by high-performance processors and graphics displays, with large local disk storage, networking capability, and running under a multitasking operating system. Workstations are still used for tasks such as computer-aided design, drafting and modelling, computation-intensive scientific and engineering calculations, image processing, architectural modelling, and computer graphics for animation and motion picture visual effects.Ralston, Anthony; Reilly, Edwin (1993). "Workstation". Encyclopedia of Computer Science (Third Edition). New York: Van Nostrand Reinhold. ISBN 0442276796.
Eventually the market segments lost any technical distinction; business computers acquired color graphics capacity and sound, and home computers and game systems used the same processors and operating systems as office-bound computers. Mass-market computers had graphics and memory comparable to dedicated workstations of a few years before. Even local area networking, originally a way to allow business computers to share expensive mass storage and peripherals, became a standard feature of a home computer.
Today a PC may be a desktop computer, a laptop computer, or a tablet computer. The most common operating systems are Microsoft Windows, Mac OS and Linux, while the most common microprocessors are the x86 and PowerPC CPUs. Software applications for personal computers include word processing, spreadsheets, games, and a myriad of personal productivity and special-purpose software. Modern personal computers often have high-speed or dial-up connections to the Internet, allowing access to the World Wide Web and a wide range of other resources. While early PCs owners usually had to write their own programs to do anything useful with the machines, today\'s users have access to a wide range of commercial and free software which is easily installed. The coming convergence of larger devices and the Personal Digital Assistants (PDAs), mobile phone and wearable computer markets which have similar functions, operating systems and even the same components, will decide if personal computer will refer to these devices."A Personal Computer To Carry In a Pocket", The New York Times. Retrieved on 2008-02-13. "Google\'s Android approach threatens no less than the personal computer itself", TalkBack on ZDNet. Retrieved on 2008-02-13. "War for the \'4th screen\'", International Herald Tribune. Retrieved on 2008-02-13. Philip Greenspun (September 2005). Mobile Phone As Home Computer. Retrieved on 2008-02-13.
One early use of the term "personal computer" appeared in a November 3, 1962, New York Times article reporting John W. Mauchly\'s vision of future computing as detailed at a recent meeting of the American Institute of Industrial Engineers. Mauchly stated, "There is no reason to suppose the average boy or girl cannot be master of a personal computer."Pocket Computer May Replace Shopping List", The New York Times, 03 November 1962.
Six years later a manufacturer took a risk at referring to their product this way when Hewlett Packard advertised their "Powerful Computing Genie" as "The New Hewlett Packard 9100A personal computer".. "9100A desktop calculator, 1968". Hewlett-Packard. Retrieved on 2008-02-13. This advertisement was deemed too extreme for the target audience and replaced with a much drier ad for the HP 9100A programmable calculator.Hewlett Packard (25 October 1966). "Restoring the Balance between Analysis and Computation" (.PDF). Science Magazine 169 (3852): 409. Retrieved on 2008-02-13. Shapiro, F.R. (December 2000). "Annals of the History of Computing" 22 (4): 70-71. IEEE Journal. doi:10.1109/MAHC.2000.887997.
During the next seven years the phrase had gained usage so when Byte magazine, published its first edition it referred to its readers as being in the "personal computing field",Carl Helmers. "What is BYTE", BYTE, October 1975, pp. 4, col 3, para 2. Retrieved on 2008-02-13. while Creative Computing defined the personal computer as a "non-(time)shared system containing sufficient processing power and storage capabilities to satisfy the needs of an individual user."Horn, B.; Winston, P.. "Personal Computers", Datamation. Retrieved on 2008-02-13. Two years later when the 1977 Trinity of preassembled small computers hit the markets, the Apple II
and the PET 2001commodore.ca | Oldest Known Commodore PET Brochure were advertised as personal computers, while the TRS-80 was a microcomputer used for household tasks including "personal financial management". By 1979 over half a million microcomputers were sold and the youth of the day had a new concept of the personal computer.Jeremy Reimer. "Total share: 30 years of personal computer market share figures; The 8-bit era (1980-1984)", Ars Technica, 14 December 2005, pp. 4. Retrieved on 2008-02-13.
On January 3 1983, the Personal Computer was the first non-human to be announced as Person of the Year by Time Magazine, in 1982.1983 Person of the Year
The initialism PC may refer generically to a personal computer, or may be intended to refer to one of the original IBM PC compatible computers, or may refer to a Microsoft Windows computer currently available.
Personal computers are normally operated by one user at a time to perform such general purpose tasks as word processing, Internet browsing, Internet faxing, e-mail and other digital messaging, multimedia playback, computer game play, computer programming, etc. The user of a modern personal computer may have significant knowledge of the operating environment and application programs, but is not necessarily interested in programming nor even able to write programs for the computer. Therefore, most software written primarily for personal computers tends to be designed with simplicity of use, or "user-friendliness" in mind. However, the software industry continuously provide a wide range of new products for use in personal computers, targeted at both the expert and the non-expert user.
An exploded view of a personal computer: 1. Monitor; 2. Motherboard; 3. CPU (Microprocessor); 4. Primary storage (RAM); 5. Expansion cards; 6. Power supply; 7. Optical disc drive; 8. Secondary storage (Hard disk); 9. Keyboard; 10. Mouse
This section describes the typical personal computer called a desktop computer because one can easily look inside the case. The other types of personal computers have the same basic setup, but usually lack the peripherals.
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A minimal setup of a typical contemporary desktop computer would be
The motherboard connects everything together. The memory card(s), graphics card and processor, are mounted directly onto the motherboard (the processor in a socket and the memory and graphics cards in expansion slots). The mass storage is connected to it with cables and can be installed in the computer case or in a separate case. Same for keyboard and mouse, except that they are external and connect to the I/O panel on the back of the computer. The monitor is also connected to the I/O panel, either through an onboard port on the motherboard, or a port on the graphics card.
Several functions (implemented by chipsets) can be integrated into the motherboard, such as typically USB and network, but also graphics and sound. But even if these are present, a separate card can be added if what is available isn\'t sufficient.
The graphics and sound card can have a break out box to keep the analog parts away from the electromagnetic radiation inside the computer case. For really large amounts of data, a tape drive can be used or (extra) hard disks can be put together in an external case.
These components can usually be put together with little knowledge, to build a computer. If something shouldn\'t go somewhere, it usually doesn\'t fit (this used to not always be the case in the past) and if it does fit it can usually do little harm.
Most personal computers are standardized to the point that purchased software is expected to run with little or no customization for the particular computer. Many PCs are also user-upgradeable, especially desktop and workstation class computers. Devices such as main memory, mass storage, even the motherboard and central processing unit may be easily replaced by an end user. This upgradeability is, however, not indefinite due to rapid changes in the personal computer industry. A PC that was considered top-of-the-line five or six years prior may be impractical to upgrade due to changes in industry standards. Such a computer usually must be totally replaced once it\'s no longer suitable for its purpose. This upgrade and replacement cycle is partially related to new releases of the primary mass-market operating system, which tends to drive the acquisition of new hardware and tends to obsolete previously serviceable hardware (see planned obsolescence).
The hardware capabilities of personal computers can sometimes be extended by the addition of expansion cards connected via an expansion bus. Some standard peripheral buses often used for adding expansion cards in personal computers as of 2005 are PCI, AGP (a high-speed PCI bus dedicated to graphics adapters), and PCI Express. Most personal computers as of 2005 have multiple physical PCI expansion slots. Many also include an AGP bus and expansion slot or a PCI Express bus and one or more expansion slots, but few PCs contain both buses.
The motherboard referred to interchangeably as systemboard or mainboard, is the primary circuit board within a personal computer. Many other components connect directly or indirectly to the motherboard. Motherboards usually contain one or more CPUs, supporting circuitry -- usually integrated circuits (ICs) providing the interface between the CPU memory and input/output peripheral circuits, main memory, and facilities for initial setup of the computer immediately after power-on (often called boot firmware or, in IBM PC compatible computers, a BIOS). In many portable and embedded personal computers, the motherboard houses nearly all of the PC\'s core components. Often a motherboard will also contain one or more peripheral buses and physical connectors for expansion purposes. Sometimes a secondary daughter board is connected with the motherboard to provide further expandability or to satisfy space constraints.
The central processing unit, or CPU, is that part of a computer which executes software program instructions. In older computers this circuitry was formerly on several printed circuit boards, but in PC class machines, has been from the first personal computers, a single integrated circuit. Nearly all PCs contain a type of CPU known as a microprocessor. The microprocessor often plugs into the motherboard using one of many different types of sockets. IBM PC compatible computers use an x86-compatible processor, usually made by Intel, AMD, VIA Technologies or Transmeta. Apple Macintosh computers were initially built with the Motorola 680x0 family of processors, then switched to the PowerPC series (a RISC architecture jointly developed by Apple Computer, IBM and Motorola), but as of 2006, Apple has switched again, this time to x86 compatible processors.
A four-megabyte RAM card measuring about 56 by 38 centimeters (twenty-two by fifteen inches); made for the VAX 8600 minicomputer (ca. 1986). Dual in-line package (DIP) Integrated circuits populate nearly the whole board; the RAM chips are the most common kind, and located in the rectangular areas to the left and right.
A PC\'s main memory is fast storage that is directly accessible by the CPU, and is used to store the currently executing program and immediately needed data. PCs use semiconductor random access memory (RAM) of various kinds such as DRAM or SRAM as their primary storage. Which exact kind depends on cost/performance issues at any particular time. Main memory is much faster than mass storage devices like hard disks or optical discs, but is usually volatile, meaning it does not retain its contents (instructions or data) in the absence of power, and is much more expensive for a given capacity than is most mass storage. Main memory is generally not suitable for long-term or archival data storage.
Internals of a Winchester hard drive with the disks removed.
Mass storage devices store programs and data even when the power is off; they do require power to perform read/write functions during usage. Although semiconductor flash memory has dropped in cost, the prevailing form of mass storage in personal computers is still the electromechanical hard disk.
The disk drives use a sealed head/disk assembly (HDA) which was first introduced by IBM\'s "Winchester" disk system. The use of a sealed assembly allowed the use of positive air pressure to drive out particles from the surface of the disk, which improves reliability.
If the mass storage controller provides for expandability, a PC may also be upgraded by the addition of extra hard disk or optical disc drives. For example, DVD-ROMs, CD-ROMs, and various optical disc recorders may all be added by the user to certain PCs. Standard internal storage device interfaces are ATA, Serial ATA, SCSI, and CF+ Type II in 2005.
The video card - otherwise called a graphics card, graphics adapter or video adapter - processes and renders the graphics output from the computer to the computer display, also called the visual display unit (VDU), and is an essential part of the modern computer. On older models, and today on budget models, graphics circuitry tended to be integrated with the motherboard but, for modern flexible machines, they are supplied in PCI, AGP, or PCI Express format.
When the IBM PC was introduced, many existing personal computers used text-only display adapters and had no graphics capability.
A laptop computer or simply laptop, also called a notebook computer or sometimes a notebook, is a small personal computer designed for mobility. Usually all of the interface hardware needed to operate the laptop, such as parallel and serial ports, graphics card, sound channel, etc., are built in to a single unit. Most laptops contain batteries to facilitate operation without a readily available electrical outlet. In the interest of saving power, weight and space, they usually share RAM with the video channel, slowing their performance compared to an equivalent desktop machine.
One main drawback of the laptop is that, due to the size and configuration of components, relatively little can be done to upgrade the overall computer from its original design. Some devices can be attached externally through ports (including via USB); however internal upgrades are not recommended or in some cases impossible, making the desktop PC more modular.
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Jimmy Carter (1976) · Anwar Sadat (1977) · Deng Xiaoping (1978) · Ayatollah Khomeini (1979) · Ronald Reagan (1980) · Lech Wałęsa (1981) · The Computer (1982) · Ronald Reagan (1983) · Peter Ueberroth (1984) · Deng Xiaoping (1985) · Corazon Aquino (1986) · Mikhail Gorbachev (1987) · The Endangered Earth (1988) · Mikhail Gorbachev (1989) · George H. W. Bush (1990) · Ted Turner (1991) · Bill Clinton (1992) · “The Peacemakers:” Yasser Arafat / F.W. de Klerk / Nelson Mandela / Yitzhak Rabin(1993) · Pope John Paul II (1994) · Newt Gingrich (1995) · David Ho (1996) · Andrew Grove (1997) · Bill Clinton / Kenneth Starr (1998) · Jeffrey P. Bezos (1999) · George W. Bush (2000) |
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