Personal computer
A
personal computer (
PC) is usually a
microcomputer whose price, size, and capabilities make it suitable for personal usage. The term was popularized by
Apple Computer with the
Apple II in the late-1970s and early-1980s, and afterwards by
IBM with the
IBM PC.
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Time share "terminals" to central computers were sometimes used before the advent of the PC, such as the smart terminal — televideo ASCII character mode terminal pictured here. |
Mainframes and large 'minicomputers'
Before their advent in the late-1970s to the early-1980s, the only computers possibly available, if the user was privileged, were "
computer-terminal based" architectures owned by large institutions. In these, the technology was called "
computer time share systems", and used
minicomputers and
mainframe computers.
Some of the first computers that might be called "personal" were early
minicomputers such as the
LINC and
PDP-8, and later on
VAX and larger minicomputers from
Data General,
Prime, and others. By today's standards they were very large (about the size of a refrigerator) and cost prohibitive (typically tens of thousands of
US dollars), and thus were rarely purchased by an individual. However, they were much smaller, less expensive, and generally simpler to operate than many of the mainframe computers of the time. Therefore, they were accessible for individual laboratories and research projects. Minicomputers largely freed these organizations from the
batch processing and bureaucracy of a commercial or university computing center.
In addition, minicomputers were relatively interactive and soon had their own
operating systems. The minicomputer
Xerox Alto (1974) is one of the computers considered to be the first personal computer, because of its
graphical user interface,
bit-mapped high resolution screen, large internal and external memory storage,
mouse, and special software.
[Rheingold, H. (2000). Tools for thought : the history and future of mind-expanding technology (New ed.). Cambridge, MA etc.: The MIT Press.] All together though, the minicomputer era largely was a precursor to personal computer usage and an intermediary step from mainframes.
Computers at home
The first generations of personal microcomputers were usually sold as kits or merely instructions, and required a somewhat skilled person to assemble and operate them. These were usually called microcomputers or
desktop computers, but the name "personal computer" was also used. Later generations were sometimes interchangeably called by the names "
home computer" and "personal computer." By the mid-1980s, "home computer" was becoming a less common label in favor of "personal computer." These computers were pre-assembled and required little technical knowledge to operate.
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.
"
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A university computer lab containing many desktop PCs |
Development of the single-chip
microprocessor was an enormous catalyst to the popularization of cheap, easy to use, and truly personal computers. Arguably the first true "personal computer" was the
Altair 8800, which brought affordable computing to an admittedly select market in the 1970s. However, it was arguably this computer that spawned the development of both
Apple Computer as well as
Microsoft, spawning the
Altair BASIC programming language interpreter, Microsoft's first product. The first generation of
microcomputers (computers based on a microprocessor) that appeared in the mid-1970s, due to the success of the
Steve Wozniak-designed Apple release, the
Apple II, were usually known as
home computers. These were less capable and in some ways less versatile than large business computers of the day. They were generally used by computer enthusiasts for learning to
program, running simple office/productivity applications, electronics interfacing, and general hobbyist pursuits.
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A release photo of the original IBM PC (ca. 1981) |
Back to business
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. This was followed by the
August 12 1981 release of the
IBM PC which would revolutionize the computer market. The
Lotus 1-2-3, a combined spreadsheet (a clone of VisiCalc), presentation graphics, and simple database application, would become the PC's own killer app. Good
word processor programs would also appear for many home computers, in particular the introduction of
Microsoft Word for the
Apple Macintosh in 1985 (While earlier versions of Word had been created for the PC, it became popular initially through the Macintosh.).
In the
January 3 1983 issue of
Time magazine, the personal computer was named the "Person of the Year" for 1982.
Today
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 brute
CPU ability.
In today's common usage, personal computer and PC usually indicate an
IBM PC compatible. Due to this association, some manufacturers of personal computers that are not IBM PCs avoid explicitly using the terms to describe their products. Mostly, the term PC is used to describe personal computers that use
Microsoft Windows operating systems.
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,
video game play,
computer programming, etc. Other more specific functions usually performed with the help of a PC include
working,
teleworking,
learning,
researching,
printing,
online banking,
online shopping and dealing
online with
public sector institutions and services. 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.
[[Image:Personal computer, exploded 5.svg|thumb|right|325px|An exploded view of a modern personal computer:
- {{Computer display|Display}}
- {{Motherboard}}
- {{Central processing unit|CPU}} ({{Microprocessor}})
- {{Primary storage}} ({{Random access memory|RAM}})
- {{Expansion card}}s
- {{Power supply}}
- {{Optical disc|Optical disc drive}}
- {{Secondary storage}} ({{Hard disk|HD}})
- {{Computer keyboard|Keyboard}}
- {{Mouse (computing)|Mouse}}
]]
Personal computers can be categorized by size and portability:
*
Desktop computers*
Laptop or notebooks*
Personal digital assistants (PDAs)*
Portable computers*
Tablet computers*
Wearable computersMost 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-upgradable, 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 is 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.
Motherboard
The motherboard (or mainboard) is the primary
circuit board for a personal microcomputer. Many other components connect directly or indirectly to the motherboard. Motherboards usually contain one or more CPUs, supporting circuitry and ICs for CPU operation, main memory, and facilities for initial setup of the computer immediately after being powered on (often called boot
firmware or 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.
Central processing unit
The central processing unit, or CPU, is the part of the computer that executes software
programs, including the
operating system. 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 processors were based on the
Power PC (a
RISC architecture) but as of 2005, Apple has used x86 compatible processors from Intel.
Main memory
A PC's main memory place (or primary storage) is fast storage space that is directly accessible by the CPU. It is generally used for storing relatively short-term data needed for software execution. Main memory is usually much faster than mass storage devices like
hard disks or
optical discs, but usually cannot retain data for more than a few fractions of a second without power and is more expensive. Therefore, it is not generally suitable for long-term or archival data storage. As with the CPU, most PCs use some form of semiconductor
random access memory such as
DRAM or
SRAM as their primary storage.
Mass storage
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Internals of a Winchester 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 drives. For example, s,
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.
Graphics - Video 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.
A
laptop computer or simply laptop (also notebook computer or notebook) is a small personal computer designed for mobility. Usually all of the peripherals needed to operate the laptop are built in to a single unit. Most laptops contain
batteries to facilitate operation without a readily available electrical outlet.
Though many personal computers are
IBM PC compatible using either Microsoft Windows or closed and open-source
Unix-likes such as
Linux, a number of other personal computer types are also popular.
A leading alternative to the IBM PC is the
Apple Macintosh, a combination of proprietary hardware and operating system. The Macintosh originally used the
Motorola 68000 series, then shifted to the IBM and Motorola
PowerPC processors. In January, 2006, Apple shifted its architecture to the same Intel processor family found in IBM compatibles, the new Mac architecture is not strictly IBM-compatibleâ€"it does not employ the
master boot record (MBR) technology used since the IBM PC, nor does it use
BIOS, using instead the
Extensible Firmware Interface (EFI) invented by
Intel. Mainstream PC's are, however, slowly starting to follow Apple's lead in adopting these technologiesâ€"
Windows Vista, will slow this process as it does not support EFI natively only through the compatibility support module
Further PC and PW (Personal Workstation) types through time:
*
Amiga (previously produced by
Commodore, now under license from Amiga Inc.)
*
Acorn Archimedes &
RiscPC*
Atari ST*
BeOS BeBox*
Pegasos*
NEC PC-9800 (At one time, in
Japan.)
*
NeXT workstations
*
Sun SPARCstation*
SGI workstations like the
SGI Indigo and
SGI OnyxThe 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".
*
Apple Computer,
Apple II,
Apple Lisa, and
Apple Macintosh*
Computer*
Desktop replacement computer*
Gaming PC*
History of computing hardware (1960s-present)*
Home computer*
Laptop*
Silent PC*
HTPC*
Microcomputer*
Minicomputer*
Mainframe computer*
Osborne 1*
Supercomputer*
Xerox Star*
Old Computers Museum (all computer types)
*
Rune's PC Museum*
The PC Guide contains detailed historical and technical information.
*
Howstuffworks' article on "How PCs Work"*
Wikicity for PC enthuiasm*
BlinkenLights Archaeological Insititute - Personal Computer Milestones What was the first personal computer?
*
"Total share: 30 years of personal computer market share figures" – From
Ars Technica
