Personal computer

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The tower of a personal computer.
The tower of a personal computer.
Personal computer and peripherals. From left to right: ink jet printer, an irrelevant TV, CRT monitor, broadband cable modem for the internet, flat bed scanner. The tower (CPU, hard drive, etc) can just be glimpsed at bottom right. The keyboard and mouse are wireless.
Personal computer and peripherals. From left to right: ink jet printer, an irrelevant TV, CRT monitor, broadband cable modem for the internet, flat bed scanner. The tower (CPU, hard drive, etc) can just be glimpsed at bottom right. The keyboard and mouse are wireless.
A personal computer.
A personal computer.
A Micron TransPort XPE laptop computer.
A Micron TransPort XPE laptop computer.

A personal computer or PC is generally a microcomputer intended to be used by one person at a time, and suitable for general purpose tasks such as word processing, programming, multimedia editing or game play, usually used to run software not written by the user. Unlike minicomputers, a personal computer is often owned by the person using it, indicating a low cost of purchase and simplicity of operation. 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.

The first generation of microcomputers were called just that, and only sold in small numbers to those able to (build them from kits or) operate them: engineers and accomplished hobbyists (for example, the Altair 8800). The second generation micros were known as home computers, and are discussed in that section.

The initials "PC" have become virtually synonymous with IBM PC compatible computers such that they are rarely used to refer to non-IBM PC compatible personal computers such as the Apple Macintosh.



An early use of the term appeared in a November 3, 1962, New York Times article reporting John W. Mauchly's vision of future computing spoken to a meeting of the American Institute of Industrial Engineers that previous day. Mauchly told the gathering, "There is no reason to suppose the average boy or girl cannot be master of a personal computer." [1]

The first computers that can be called 'personal' were the first non-mainframe computers, the LINC and the PDP-8. By today's standards they were big (about the size of a refrigerator), expensive (around $50,000 US), and had small magnetic core memories (about 4096 12-bit words for the LINC).

However, they were small enough and cheap enough for individual laboratories and research projects to use, freeing them from the batch processing and bureaucracy of the typical industrial or university computing center. In addition, they were moderately interactive and soon had their own operating systems. Eventually, this category became known as the mini-computer, usually with time-sharing and program development facilities. Eventually, the mini-computer grew up to encompass the VAX and larger mini-computers from Data General, Prime, and others. Deployment of mini-computer systems was a model for how personal computers would be used, but few of the mini-computer makers managed to profit from it.

Development of the single-chip microprocessor changed everything, since it dropped the cost of purchase of a computer by an order of magnitude or more.

The first generation of microcomputers that started to appear in the mid 1970s (see home computers) were less powerful and in some ways less versatile than business computers of the day (but in other ways more versatile, in terms of built-in sound and graphics capabilities), and were generally used by computer enthusiasts for learning to program, for running simple office/productivity applications, for electronics interfacing, and/or games, as well as for accessing BBS's, general online services such as CompuServe, The Source, or Genie, or platform-specific services such as Quantum Link (US) or Compunet (UK).

It was the launch of the VisiCalc spreadsheet, initially for the Apple II and later for the Atari 8-bit family, Commodore PET, and IBM PC that became the "killer app" that turned the microcomputer into a business tool. Later, Lotus 1-2-3, a combined spreadsheet (partly based on VisiCalc), presentation graphics, and simple database application, became the PCs own killer app. Good word processor programs also appeared for many home computers. The low cost of personal computers led to great popularity in the home and business markets during the 1980s. In 1982, Time magazine named the personal computer its Man of the Year.

During the 1990s, the power of personal computers increased radically, blurring the formerly sharp distinction between personal computers and multi-user computers such as mainframes. Today higher-end computers often distinguish themselves from personal computers by greater reliability or greater ability to multitask, rather than by straight CPU power.


Personal computers can be categorized by size and portability:

Many mass-market IBM PC compatible and Apple Macintosh personal computers are standardized to the point that purchased software is expected to run with little or no customization for the particular computer. Often memory, and peripherals such as video boards and disk storage are easily upgradeable, even by the end user, and even the motherboard can in some cases be changed to upgrade the power of the central processor. Such upgradeability is not indefinite since major changes in the personal computer industry occur every three to five years; a machine that was considered top-of-the-line say five or six years ago may be impractical to upgrade due to changes in processors, memory, and peripherals. This upgrade cycle is in part linked 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. The standard expansion bays for personal computers as of 2005 are PCI, AGP, and PCI Express. All personal computers as of 2005 have multiple PCI slots, and all but the cheapest prebuilt PCs have either a single AGP or at least one PCI Express slot, but rarely both. A PC may also be upgraded by the addition of extra drives (DVD, CD-ROM, flash drive, Hard drive, etc). Standard internal storage device interfaces are ATA, Serial ATA, SCSI, and CF+ Type II in 2005.


Main article: PC motherboard

The motherboard is the primary circuit board for a computer. Most other computer components plug directly into the motherboard to allow them to exchange information. Motherboards usually hold a chipset, BIOS, nonvolatile BIOS memory, parallel port, PS/2 keyboard and mouse ports and expansion bays. Sometimes a secondary daughter board is plugged into the motherboard to provide more expansion bays and to cut down on its size.

Central processing unit

Main article: central processing unit

The Central processing unit or CPU is the part of the computer that performs most of the calculations that make programs or operating systems run. The CPU plugs directly into the motherboard by one of many different types of sockets. Most IBM PC compatible computers use an x86-compatible processor made by Intel, AMD, VIA Technologies or Transmeta.

RAM - memory

Main article: random access memory

The Random Access Memory of the computer is the "short-term-memory" of the PC, It is much faster than the mass storage devices like Harddisk or CD-ROM, but its contents are lost when the Power is turned off.

Hard disk drive

Main article: 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. This technology is now industry standard, with costs, capacities and access speeds which conform to Moore's law.

PSU - power supply unit

Main article: power supply

Essential. Provides steady DC supply from a domestic AC source. Many problems with Old PCs can be traced to a faulty or overheating PSU. Newer power supplies often have voltage regulators that will shut down the computer if the power supply is under strain.

Graphics - video Card

Main article: graphics card

The graphics card - otherwise called a graphics adapter, video adapter, or video card - processes and renders the graphics output from the computer to the VDU or computer monitor and is an essential part of the modern computer. On older and budget models graphics cards tended to be integrated with the motherboard but, more commonly, they are supplied in PCI, AGP, or PCI Express format. Graphic cards are also the most glamorised computer component as it is the component which creates all the visual effects on the computer which is essential for playing games

Non IBM-compatible personal computers

Though many personal computers are IBM PC compatible using either Microsoft Windows or closed and open-source Unixes such as Linux, a number of other personal computer types are still popular. The leading alternative is Apple Computer's Power Macintosh platform, based on the PowerPC microprocessor (although Apple has announced[2] a transition to Intel microprocessors beginning in 2006).

Further PC and PW (Personal Workstation) types through time:

The term "personal computer" is often avoided by advocates of the above computer systems, ostensibly because of the association it has to the "PC" in "IBM PC".

See also

Display and keyboard
Display and keyboard


  • ^  "Pocket Computer May Replace Shopping List", New York Times, 3 November 1962.

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