An
artist's depiction of a 2000s-era personal computer of the desktop
style, which includes a metal case with the computing components, a
display monitor and a keyboard (mouse not shown).
A personal computer (PC) is a multi-purpose computer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or technician. Unlike large costly minicomputer and mainframes, time-sharing by many people at the same time is not used with personal computers.
Institutional or corporate computer owners in the 1960s had to
write their own programs to do any useful work with the machines. While
personal computer users may develop their own applications, usually
these systems run commercial software, free-of-charge software ("freeware") or free and open-source software,
which is provided in ready-to-run form. Software for personal computers
is typically developed and distributed independently from the hardware
or operating system manufacturers.
Many personal computer users no longer need to write their own programs
to make any use of a personal computer, although end-user programming
is still feasible. This contrasts with mobile systems, where software is
often only available through a manufacturer-supported channel, and end-user program development may be discouraged by lack of support by the manufacturer.
Since the early 1990s, Microsoft operating systems and Intel hardware have dominated much of the personal computer market, first with MS-DOS and then with Windows. Alternatives to Microsoft's Windows operating systems occupy a minority share of the industry. These include Apple's macOS and free and open-source Unix-like operating systems such as Linux. Advanced Micro Devices (AMD) provides the main alternative to Intel's processors.
Terminology
"PC" is an initialism for "personal computer". The IBM Personal Computer
incorporated the designation in its model name. It is sometimes useful
to distinguish personal computers of the "IBM Personal Computer" family
from personal computers made by other manufacturers. For example, "PC"
is used in contrast with "Mac", an Apple Macintosh computer. Since none of these Apple products were mainframes or time-sharing
systems, they were all "personal computers" and not "PC" (brand)
computers
History
Commodore PET in 1983 (at American Museum of Science and Energy), an early example of a personal computer
The “brain” [computer] may one day come down to our level [of the common people] and help with our income-tax and book-keeping calculations. But this is speculation and there is no sign of it so far.
— British newspaper The Star in a June 1949 news article about the EDSAC computer, long before the era of the personal computers.
In the history of computing, early experimental machines could be operated by a single attendant. For example, ENIAC which became operational in 1946 could be run by a single, albeit highly trained, person. This mode pre-dated the batch programming, or time-sharing modes with multiple users connected through terminals
to mainframe computers. Computers intended for laboratory,
instrumentation, or engineering purposes were built, and could be
operated by one person in an interactive fashion. Examples include such
systems as the Bendix G15 and LGP-30of 1956, the Programma 101 introduced in 1964, and the Soviet MIR
series of computers developed from 1965 to 1969. 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 Italian Programma 101 was a programmable calculator produced by Olivetti in 1964
In what was later to be called the Mother of All Demos, SRI researcher Douglas Engelbart
in 1968 gave a preview of what would become the staples of daily
working life in the 21st century: e-mail, hypertext, word processing,
video conferencing, and the mouse. The demonstration required technical
support staff and a mainframe time-sharing computer that were far too
costly for individual business use at the time.
The development of the microprocessor,
with widespread commercial availability starting in the mid 1970's,
made computers cheap enough for small businesses and individuals to own.
Early personal computers—generally called microcomputers—were often sold in a kit
form and in limited volumes, and were of interest mostly to hobbyists
and technicians. Minimal programming was done with toggle switches to
enter instructions, and output was provided by front panel lamps.
Practical use required adding peripherals such as keyboards, computer displays, disk drives, and printers.
Micral N was the earliest commercial, non-kit microcomputer based on a microprocessor, the Intel 8008. It was built starting in 1972, and few hundred units were sold. This had been preceded by the Datapoint 2200
in 1970, for which the Intel 8008 had been commissioned, though not
accepted for use. The CPU design implemented in the Datapoint 2200
became the basis for x86 architecture used in the original IBM PC and its descendants.
In 1973, the IBM Los Gatos Scientific Center developed a portable computer prototype called SCAMP (Special Computer APL Machine Portable) based on the IBM PALM processor with a Philips compact cassette drive, small CRT, and full function keyboard. SCAMP emulated an IBM 1130 minicomputer in order to run APL/1130. In 1973, APL was generally available only on mainframe computers, and most desktop sized microcomputers such as the Wang 2200 or HP 9800 offered only BASIC. Because SCAMP was the first to emulate APL/1130 performance on a portable, single user computer, PC Magazine in 1983 designated SCAMP a "revolutionary concept" and "the world's first personal computer". This seminal, single user portable computer now resides in the Smithsonian Institution, Washington, D.C.. Successful demonstrations of the 1973 SCAMP prototype led to the IBM 5100
portable microcomputer launched in 1975 with the ability to be
programmed in both APL and BASIC for engineers, analysts, statisticians,
and other business problem-solvers. In the late 1960s such a machine
would have been nearly as large as two desks and would have weighed
about half a ton.
Another desktop portable APL machine, the MCM/70, was demonstrated in 1973 and shipped in 1974. It used the Intel 8008 processor.
A seminal step in personal computing was the 1973 Xerox Alto, developed at Xerox's Palo Alto Research Center (PARC). It had a graphical user interface (GUI) which later served as inspiration for Apple's Macintosh, and Microsoft's Windows operating system. The Alto was a demonstration project, not commercialized, as the parts were too expensive to be affordable.
Also in 1973 Hewlett Packard introduced fully BASIC
programmable microcomputers that fit entirely on top of a desk,
including a keyboard, a small one-line display, and printer. The Wang 2200 microcomputer of 1973 had a full-size cathode ray tube (CRT) and cassette tape storage. These were generally expensive specialized computers sold for business or scientific uses. 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 1975.
Altair 8800 computer
1974 saw the introduction of what is considered by many to be the first true "personal computer", the Altair 8800 created by Micro Instrumentation and Telemetry Systems (MITS). Based on the 8-bit Intel 8080 Microprocessor, the Altair is widely recognized as the spark that ignited the microcomputer revolution as the first commercially successful personal computer. The computer bus designed for the Altair was to become a de facto standard in the form of the S-100 bus, and the first programming language for the machine was Microsoft's founding product, Altair BASIC.
In 1976, Steve Jobs and Steve Wozniak sold the Apple I
computer circuit board, which was fully prepared and contained about 30
chips. The Apple I computer differed from the other kit-style hobby
computers of era. At the request of Paul Terrell, owner of the Byte Shop,
Jobs and Wozniak were given their first purchase order, for 50 Apple I
computers, only if the computers were assembled and tested and not a kit
computer. Terrell wanted to have computers to sell to a wide range of
users, not just experienced electronics hobbyists who had the soldering
skills to assemble a computer kit. The Apple I
as delivered was still technically a kit computer, as it did not have a
power supply, case, or keyboard when it was delivered to the Byte Shop.
The first successfully mass marketed personal computer to be announced was the Commodore PET after being revealed in January 1977. However, it was back-ordered and not available until later that year. Three months later (April), the Apple II (usually referred to as the "Apple") was announced with the first units being shipped 10 June 1977, and the TRS-80 from Tandy Corporation / Tandy Radio Shack
following in August 1977, which sold over 100,000 units during its
lifetime. Together, these 3 machines were referred to as the "1977
trinity". Mass-market, ready-assembled computers had arrived, and
allowed a wider range of people to use computers, focusing more on
software applications and less on development of the processor hardware.
IBM 5150, released in 1981
The 8-bit PMD 85 personal computer produced in 1985–1990 by the Tesla company in the former socialist Czechoslovakia
During the early 1980s, home computers
were further developed for household use, with software for personal
productivity, programming and games. They typically could be used with a
television already in the home as the computer display, with low-detail
blocky graphics and a limited color range, and text about 40 characters
wide by 25 characters tall. Sinclair Research, a UK company, produced the ZX Series—the ZX80 (1980), ZX81 (1981), and the ZX Spectrum; the latter was introduced in 1982, and totaled 8 million unit sold. Following came the Commodore 64, totaled 17 million units sold.
In the same year, the NEC PC-98 was introduced, which was a very popular personal computer that sold in more than 18 million units. Another famous personal computer, the revolutionary Amiga 1000, was unveiled by Commodore
on July 23, 1985. The Amiga 1000 featured a multitasking, windowing
operating system, color graphics with a 4096-color palette, stereo
sound, Motorola 68000 CPU, 256 KB RAM, and 880 KB 3.5-inch disk drive,
for US$1,295.
Somewhat larger and more expensive systems (for example, running CP/M), or sometimes a home computer with additional interfaces and devices, although still low-cost compared with minicomputers and mainframes,
were aimed at office and small business use, typically using "high
resolution" monitors capable of at least 80 column text display, and
often no graphical or color drawing capability.
Workstations
were characterized by high-performance processors and graphics
displays, with large-capacity local disk storage, networking capability,
and running under a multitasking operating system. Eventually, due to
the influence of the IBM PC on the personal computer market,
personal computers and home computers lost any technical distinction.
Business computers acquired color graphics capability and sound, and
home computers and game systems users used the same processors and
operating systems as office workers. Mass-market computers had graphics
capabilities 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 personal computers used at home.
In 1982 "The Computer" was named Machine of the Year by Time
magazine. In the 2010s, several companies such as Hewlett-Packard and
Sony sold off their PC and laptop divisions. As a result, the personal
computer was declared dead several times during this period.
Types
Stationary
Workstation
Sun SPARCstation 1+ from the early 1990s, with a 25 MHz RISC processor
A workstation is a high-end personal computer designed for technical,
mathematical, or scientific applications. Intended primarily to be used
by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. Workstations are used for tasks such as computer-aided design, drafting and modeling, computation-intensive scientific and engineering calculations, image processing, architectural modeling, and computer graphics for animation and motion picture visual effects.
Desktop computer
A Dell OptiPlex desktop computer
Before the widespread use of PCs, a computer that could fit on a desk was remarkably small, leading to the "desktop" nomenclature. More recently, the phrase usually indicates a particular style of computer case. Desktop computers come in a variety of styles ranging from large vertical tower cases to small models which can be tucked behind an LCD monitor.
The term "desktop" typically refers to a computer with a vertically aligned computer case that holds the systems hardware
components such as the motherboard, processor chip, other internal
operating parts. Desktop computers have an external monitor with a
display screen and an external keyboard, which are plugged into USB ports on the back of the computer case. Desktop computers are popular for home and business computing applications as they leave space on the desk for multiple monitors.
Gaming computer
A gaming computer is a standard desktop computer that typically has high-performance hardware, such as a more powerful video card, processor and memory, in order to handle the requirements of demanding video games, which are often simply called "PC games". A number of companies, such as Alienware, manufacture prebuilt gaming computers, and companies such as Razer and Logitech market mice, keyboards and headsets geared toward gamers.
All-in-one
All-in-one PCs (also known as single-unit PCs) are a subtype of
desktop computer that combines the monitor and processor within a single
unit. A separate keyboard and mouse are standard input devices, with
some monitors including touchscreen
capability. The processor and other working components are typically
reduced in size relative to standard desktops, located behind the
monitor, and configured similarly to laptops.
Nettop
A subtype of desktops, called nettops, was introduced by Intel in February 2008, characterized by low cost and lean functionality. A similar subtype of laptops (or notebooks) is the netbook, described below. The product line features the new Intel Atom processor, which specifically enables nettops to consume less power and fit into small enclosures.
Home theater PC
An Antec Fusion V2 home theater PC, with a keyboard placed on top of it
A home theater PC (HTPC) is a convergence device that combines the functions of a personal computer and a digital video recorder. It is connected to a TV set or an appropriately sized computer display,
and is often used as a digital photo viewer, music and video player, TV
receiver, and digital video recorder. HTPCs are also referred to as
media center systems or media servers. The general goal in a HTPC is usually to combine many or all components of a home theater
setup into one box. More recently, HTPCs gained the ability to connect
to services providing on-demand movies and TV shows. HTPCs can be
purchased pre-configured with the required hardware and software needed
to add television programming to the PC, or can be cobbled together out
of discrete components, what is commonly done with software support from
MythTV, Windows Media Center, GB-PVR, SageTV, Famulent or LinuxMCE.
Portable
The potential utility of portable computers was apparent early on. Alan Kay described the Dynabook in 1972, but no hardware was developed. The Xerox NoteTaker was produced in a very small experimental batch around 1978. TheIBM 5100 could be fit into a transport case, making it a portable computer in 1975, but with a 50 lb overall weight.
Suitcase
Before
the introduction of the IBM PC, portable computers consisting of a
processor, display, disk drives and keyboard, in a suit-case style
portable housing, allowed users to bring a computer home from the office
or to take notes at a classroom. Examples include the Osborne 1 and Kaypro; and the Commodore SX-64.
These machines were AC powered and included a small CRT display
screen. The form factor was intended to allow these systems to be taken
on board an airplane as carry-on baggage, though their high power demand
meant that they could not be used in flight. The integrated CRT display
made for a relatively heavy package, but these machines were more
portable than their contemporary desktop equals. Some models had
standard or optional connections to drive an external video monitor,
allowing a larger screen or use with video projectors.
IBM PC-compatible suitcase format computers became available soon after the introduction of the PC, with the Compaq Portable being a leading example of the type. Later models included a hard drive to give roughly equivalent performance to contemporary desk top computers.
The development of thin plasma display and LCD screens permitted a
somewhat smaller form factor, called the "lunchbox" computer. In this
packaging, the screen formed one side of the enclosure, with a
detachable keyboard and one or two half-height disk drives, mounted
facing the ends of the computer. Some variations included a battery,
allowing operation away from AC outlets.
Notebook
Notebook computers such as the TRS 80 Model 100 and Epson HX-20 had roughly the plan dimensions of a sheet of typing paper (ANSI A or ISO A4).
These machines had a keyboard with slightly reduced dimensions compared
to a desktop system, and a fixed LCD display screen coplanar with the
keyboard. These displays were usually small, with 8 to 16 lines of
text, sometimes only 40 columns line length. However, these machines
could operate for extended times on disposable or rechargeable
batteries. Although they did not usually include internal disk drives,
this form factor often included a modem
for telephone communication and often had provisions for external
cassette or disk storage. Later, clam-shell format laptop computers with
similar small plan dimensions were also called "notebooks".
Laptop
A laptop computer
A laptop computer is designed for portability. Laptops usually have "clamshell"
design, in which the keyboard and computer components are on one panel
and a flat display screen on a second panel, which is hinged to the
first panel. The laptop is opened for use and closed for transport.
Closing the laptop also protects the screen and keyboard during
transportation. Laptops generally have a rechargeable battery,
enhancing their portability. To power, weight and space, laptop
graphics cards are in many cases integrated into the CPU or chip set and
use system RAM, resulting in reduced graphics performance when compared
to an equivalent desktop machine. For this reason, desktop computers are
usually preferred over laptops for gaming purposes.
Unlike desktop computers, only minor internal upgrades are
feasibly owing to the limited space and power available. Some internal
upgrades to laptops, such as memory and hard disk drive upgrades are
often easily performed, while a display or keyboard upgrade is usually
difficult or impossible. Just like desktops, laptops also have the same
input and output ports for connecting to a wide variety of devices,
including external displays, mice, cameras, storage devices and
keyboards, which may be attached externally through USB ports and other
less common ports such as external video. Laptops are also a little more
expensive compared to desktops, as the miniaturized components for
laptops themselves are expensive.
Desktop replacement
An Acer Aspire desktop replacement laptop
A desktop replacement computer is a portable computer that provides the full capabilities of a desktop computer.
Such computers are often actually large laptops. Because of their
increased size, this class of computers usually includes more powerful
components and a larger display than generally found in smaller portable
computers, and can have a relatively limited battery capacity or none
at all in some cases. Some use a limited range of desktop components to
provide better performance at the expense of battery life. Desktop
replacement computers are sometimes called desknotes, as a portmanteau of words "desktop" and "notebook", though the term is also applied to desktop replacement computers in general.
Netbook
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Netbooks, also called mini notebooks or subnotebooks, are a subgroup of laptops acting as a category of small, lightweight and inexpensive laptop computers suited for general computing tasks and accessing web-based applications.
They are often marketed as "companion devices", with an intention to
augment other ways in which a user can access computer resources. Walt Mossberg called them a "relatively new category of small, light, minimalist and cheap laptops." By August 2009, CNET called netbooks "nothing more than smaller, cheaper notebooks." Initially, the primary defining characteristic of netbooks was the lack of an optical disc drive, requiring it to be a separate external device. This has become less important as flash memory devices have gradually increased in capacity, replacing the writable optical disc (e.g. CD-RW, DVD-RW) as a transportable storage medium.
At their inception in late 2007—as smaller notebooks optimized for low weight and low cost—netbooks omitted key features (e.g., the optical drive),
featured smaller screens and keyboards, and offered reduced
specifications and computing power. Over the course of their evolution,
netbooks have ranged in their screen sizes from below five inches to over 13 inches, with weights around ~1 kg (2–3 pounds). Often significantly less expensive than other laptops,
by mid-2009 netbooks had been offered to users "free of charge", with
an extended service contract purchase of a cellular data plan.
In the short period since their appearance, netbooks have grown in size
and features, converging with new smaller and lighter notebooks. By
mid-2009, CNET noted that "the specs are so similar that the average
shopper would likely be confused as to why one is better than the
other," noting "the only conclusion is that there really is no
distinction between the devices."
Tablet
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HP Compaq tablet PC with rotating/removable keyboard
A tablet uses a touchscreen display, which can be controlled using either a stylus
pen or finger. Some tablets may use a "hybrid" or "convertible" design,
offering a keyboard that can either be removed as an attachment, or a
screen that can be rotated and folded directly over top the keyboard.
Some tablets may use desktop-PC operating system such as Windows or
Linux, or may run an operating system designed primarily for tablets.
Many tablet computers have USB ports, to which a keyboard or mouse can
be connected.
Smartphone
The LG G4, a typical smartphone
Smartphones are often similar to tablet computers, the difference being that smartphones always have cellular integration. They are generally smaller than tablets, and may not have a slate form factor.
Ultra-mobile PC
A Samsung Q1 Ultra UMPC
The ultra-mobile PC (UMP) is a small tablet computer. It was developed by Microsoft, Intel and Samsung, among others. Current UMPCs typically feature the Windows XP, Windows Vista, Windows 7, or Linux operating system, and low-voltage Intel Atom or VIA C7-M processors.
Pocket PC
An O2 pocket PC
A pocket PC is a hardware specification for a handheld-sized computer (personal digital assistant, PDA) that runs the Microsoft Windows Mobile operating system. It may have the capability to run an alternative operating system like NetBSD or Linux. Pocket PCs have many of the capabilities of desktop PCs. Numerous applications are available for handhelds adhering to the Microsoft Pocket PC specification, many of which are freeware. Microsoft-compliant Pocket PCs can also be used with many other add-ons like GPS receivers, barcode readers, RFID
readers and cameras. In 2007, with the release of Windows Mobile 6,
Microsoft dropped the name Pocket PC in favor of a new naming scheme:
devices without an integrated phone are called Windows Mobile Classic
instead of Pocket PC, while devices with an integrated phone and a touch
screen are called Windows Mobile Professional.
Hardware
An exploded view of a personal computer and peripherals (some of which are optional):
Computer hardware
is a comprehensive term for all physical parts of a computer, as
distinguished from the data it contains or operates on, and the software
that provides instructions for the hardware to accomplish tasks.
Some sub-systems of a personal computer may contain processors that run a
fixed program, or firmware, such as a keyboard controller. Firmware usually is not changed by the end user of the personal computer.
Most 2010s-era computers only require users to plug in the power supply, monitor, and other cables. A typical desktop computer consists of a computer case (or "tower"), a metal chassis that holds the power supply, motherboard, hard disk drive, and often an optical disc drive. Most towers have empty space where users can add additional components. External devices such as a computer monitor or visual display unit, keyboard, and a pointing device (mouse) are usually found in a personal computer.
The motherboard connects all processor, memory and peripheral devices together. The RAM, graphics card and processor are in most cases mounted directly onto the motherboard. The central processing unit (microprocessor chip) plugs into a CPU socket,
while the memory modules plug into corresponding memory sockets. Some
motherboards have the video display adapter, sound and other peripherals
integrated onto the motherboard, while others use expansion slots for graphics cards, network cards, or other I/O devices. The graphics card or sound card may employ a break out box to keep the analog parts away from the electromagnetic radiation
inside the computer case. Disk drives, which provide mass storage, are
connected to the motherboard with one cable, and to the power supply
through another cable. Usually, disk drives are mounted in the same case
as the motherboard; expansion chassis are also made for additional disk
storage.
For large amounts of data, a tape drive
can be used or extra hard disks can be put together in an external
case. The keyboard and the mouse are external devices plugged into the
computer through connectors on an I/O panel on the back of the computer
case. The monitor is also connected to the input/output (I/O) panel,
either through an onboard port on the motherboard, or a port on the
graphics card. Capabilities of the personal computers hardware can
sometimes be extended by the addition of expansion cards connected via an expansion bus. Standard peripheral buses often used for adding expansion cards in personal computers include PCI, PCI Express (PCIe), and AGP
(a high-speed PCI bus dedicated to graphics adapters, found in older
computers). Most modern personal computers have multiple physical PCI
Express expansion slots, with some of the having PCI slots as well.
Computer case
An empty ATX case lying on its side
A computer case is an enclosure that contains the main components of a computer. They are usually constructed from steel or aluminum combined with plastic, although other materials such as wood and tempered glass
have been used for specialized units. Cases are available in different
sizes and shapes; the size and shape of a computer case are usually
determined by the configuration of the motherboard
that it is designed to accommodate since this is the largest and most
central component of most computers. The most popular style for desktop
computers is ATX, although microATX and similar layouts became very popular for a variety of uses. Companies like Shuttle Inc. and AOpen have popularized small cases, for which FlexATX is the most common motherboard size. In the 1990s, desktop computer cases were larger and taller than 2010-era computer cases.
Power supply unit
Computer power supply unit with top cover removed
The power supply unit (PSU) converts general-purpose mains AC electricity to direct current
(DC) for the other components of the computer. The rated output
capacity of a PSU should usually be about 40% greater than the
calculated system power consumption needs to be obtained by adding up
all the system components. This protects against overloading the supply,
and guards against performance degradation. Power supply capacities
range from 250 to 2000 watts for desktop computers.
Processor
The central processing unit (CPU) is a part of a computer that executes instructions of a software program. In newer PCs, the CPU contains over a million transistors in one integrated circuit chip called the microprocessor. In most cases, the processor plugs directly into the motherboard. The processor chip may have a heat sink and a fan attached for cooling. A large number of computers today are suited to run an x86-compatible microprocessor manufactured by Intel, AMD, or VIA Technologies.
Motherboard
A motherboard without processor, memory and expansion cards, cables
The motherboard, also referred to as system board or main board, is the primary circuit board
within a personal computer, and other major system components plug
directly into it or via a cable. A motherboard contains a
microprocessor, the CPU supporting circuitry (mostly integrated circuits)
that provide the interface between 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 or UEFI).
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 to the motherboard to provide further expandability or to satisfy space constraints.
Main memory
1 GB DDR SDRAM PC-3200 module
A PC's main memory is a fast primary storage
device 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, SDRAM or SRAM
as their primary storage. Which exact kind is used depends on
cost/performance issues at any particular time. Main memory is much
faster than mass storage devices like hard disk drives or optical discs, but is usually volatile,
meaning that 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. As a result, main memory is generally not
suitable for long-term or archival data storage.
Storage drive
A 3.5" hard drive with the cover removed
Mass storage devices store programs and data even when the power is
off; they do require power to perform read and write functions during
usage. Although flash memory has dropped in cost, the prevailing form of mass storage in personal computers is still the hard disk drive.
If the mass storage controller provides additional ports for
expandability, a PC may also be upgraded by the addition of extra hard
disk or optical disc drives. For example, BD-ROMs, DVD-RWs,
and various optical disc recorders may all be added by the user to
certain PCs. Standard internal storage device connection interfaces are PATA, SATA and SCSI. Solid state drives (SSDs)
are a much faster replacement for traditional mechanical hard disk
drives but are also more expensive in terms of cost per gigabyte. Solid
state drives connect using several connectors, including SATA, M.2, and U.2. Some models use the NVMe protocol, which have vastly improved performance over standard hard disk drives and older SSDs that use the older AHCI protocol.
Visual display unit
A visual display unit, computer monitor or just display, is a piece of electrical equipment, usually separate from the computer case, which displays visual images without producing a permanent computer record. A display device was usually a CRT in the 1980s, but by the 2000s, flat panel displays such as a TFT LCD had largely replaced the bulkier, heavier CRT screens. Multi-monitor
setups are quite common in the 2010s, as they enable a user to display
multiple programs at the same time (e.g., an email inbox and a word
processing program). The display unit houses an electronic circuitry that generates its picture from signals received from the computer. Within the computer, either integral to the motherboard or plugged into it as an expansion card, there is pre-processing circuitry to convert the microprocessor's output data
to a format compatible with the display unit's circuitry. The images
from computer monitors originally contained only text, but as graphical user interfaces
emerged and became common, they began to display more images and
multimedia content. The term "monitor" is also used, particularly by
technicians in broadcasting television, where a picture of the broadcast data is displayed to a highly standardized reference monitor for confidence checking purposes.
Video card
A GTX 1070 video card
The video card—otherwise
called a graphics card, graphics adapter or video adapter—processes the
graphics output from the motherboard and transmits it to the display.
It is an essential part of modern multimedia-enriched computing.
Graphics circuitry may be integrated with the motherboard, or may be on
cards istalled in PCI, AGP, or PCI Express
slots. When the IBM PC was introduced, most existing business-oriented
personal computers used text-only display adapters and had no graphics
capability. Home computers at that time had graphics compatible with
television signals, but with low resolution owing to the limited memory
available to the eight-bit processors available at the time.
Keyboard
A "Model M" IBM computer keyboard from the early 1980s. Commonly called the "Clicky Keyboard" due to its buckling spring key spring design, which gives the keyboard its iconic 'click' sound with each keystroke.
A keyboard
is an arrangement of buttons that each correspond to a function,
letter, or number. They are the primary devices used for inputting text.
In most cases, they contain an array of keys specifically organized
with the corresponding letters, numbers, and functions printed or
engraved on the button. They are generally designed around an operators
language, and many different versions for different languages exist. In
English, the most common layout is the QWERTY layout, which was originally used in typewriters.
They have evolved over time, and have been modified for use in
computers with the addition of function keys, number keys, arrow keys,
and keys specific to an operating system. Often, specific functions can
be achieved by pressing multiple keys at once or in succession, such as
inputting characters with accents or opening a task manager. Programs
use keyboard shortcuts very differently and all use different keyboard
shortcuts for different program specific operations, such as refreshing a
web page in a web browser
or selecting all text in a word processor. In addition to the
alphabetic keys found on a typewriter, computer keyboards typically have
a numeric keyboard and a row of function keys and special keys, such as CTRL, ALT, DEL and Esc.
Many keyboards include LED lights under the keys that increase the visibility of the letters or symbols in dark environments.
Mouse
A selection of computer mice built between 1986 and 2007
A computer mouse
is a small handheld device that users hold and slide across a flat
surface, pointing at various elements of a graphical user interface with
an on-screen cursor, and selecting and moving objects using the mouse buttons. Mice may be plugged into a dedicated mouse socket, or a USB
port, or, may be connected wirelessly. Mice include one or more buttons
to allow a user to signal the computer to carry out some operation,
such as selecting an item from a menu of choices on the screen. A
mouse may have a scroll wheel, to allow users to move the displayed
image. The scroll wheel can also be pressed down, and used as a third
button. Some mouse wheels may be tilted from side to side to allow
sideways scrolling. Different programs make use of these functions
differently, and may scroll horizontally by default with the scroll
wheel, open different menus with different buttons, etc. These functions
may be also user-defined through software utilities. Mechanical mice
used a ball, which drove pulse generators to detect movement along
"north-south" or "east-west" axies. Optical mice use a special mouse pad
with a printed grid to allow detection of motion, or else use an
imaging chip that allows detection of motion on almost any opaque
surface.
Other components
A
proper ergonomic design of a personal computer workplace is necessary
to prevent repetitive strain injuries, which can develop over time and
can lead to long-term disability.
All computers require either fixed or removable storage for their operating system, programs and user-generated material. Early home computers used compact audio cassettes
for file storage; these were at the time a very low cost storage
solution, but were displaced by floppy disk drives when manufacturing
costs dropped, by the mid-1980s. Initially, the 5.25-inch and 3.5-inch floppy drives
were the principal forms of removable storage for backup of user files
and distribution of software. As memory sizes increased, the capacity
of the floppy did not keep pace; the Zip drive
and other higher-capacity removable media were introduced but never
became as prevalent as the floppy drive. By the late 1990s, the optical drive, in CD and later DVD and Blu-ray Disc
forms, became the main method for software distribution, and writeable
media provided means for data backup and file interchange. As a result,
floppy drives became uncommon in desktop personal computers since about
2000, and were dropped from many laptop systems even earlier.
A second generation of tape recorders was provided when videocassette recorders
were pressed into service as backup media for larger disk drives. All
these systems were less reliable and slower than purpose-built magnetic
tape drives. Such tape drives were uncommon in consumer-type personal
computers but were a necessity in business or industrial use.
Interchange of data such as photographs from digital cameras is greatly
expedited by installation of a card reader, which is often compatible with several forms of flash memory devices. It is usually faster and more convenient to move large amounts of data by removing the card from the mobile device, instead of communicating with the mobile device through a USB interface.
A USB flash drive performs much of the data transfer and backup functions formerly done with floppy drives, Zip disks
and other devices. Mainstream operating systems for personal computers
provide built-in support for USB flash drives, allowing interchange even
between computers with different processors and operating systems. The
compact size and lack of moving parts or dirt-sensitive media, combined
with low cost and high capacity, have made USB flash drives a popular
and useful accessory for any personal computer user.
The operating system can be located on any storage, but is typically installed on a hard disk or solid-state drive. A Live CD
represents the concept of running an operating system directly from a
CD. While this is slow compared to storing the operating system on a
hard disk drive, it is typically used for installation of operating
systems, demonstrations, system recovery, or other special purposes.
Large flash memory is currently more expensive than hard disk drives of
similar size (as of mid-2014) but are starting to appear in laptop
computers because of their low weight, small size and low power
requirements. Computer communications involve internal modem cards, modems, network adapter cards, and routers. Common peripherals and adapter cards include headsets, joysticks, microphones, printers, scanners, sound adapter cards (as a separate card rather than located on the motherboard), speakers and webcams.
Software
A screenshot of the LibreOffice Writer software
Computer software is any kind of computer program, procedure, or documentation that performs some task on a computer system. The term includes application software such as word processors that perform productive tasks for users, system software such as operating systems that interface with computer hardware to provide the necessary services for application software, and middleware that controls and co-ordinates distributed systems.
Software applications are common for word processing, Internet browsing, Internet faxing, e-mail and other digital messaging, multimedia playback, playing of computer game, and computer programming.
The user 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.
Operating system
An operating system (OS) manages computer resources and provides programmers with an interface
used to access those resources. An operating system processes system
data and user input, and responds by allocating and managing tasks and
internal system resources as a service to users and programs of the
system. An operating system performs basic tasks such as controlling and
allocating memory, prioritizing system requests, controlling input and output devices, facilitating computer networking, and managing files.
Common contemporary desktop operating systems are Microsoft Windows, macOS, Linux, Solaris and FreeBSD.
Windows, macOS, and Linux all have server and personal variants. With
the exception of Microsoft Windows, the designs of each of them were
inspired by or directly inherited from the Unix operating system, which was developed at Bell Labs beginning in the late 1960s and spawned the development of numerous free and proprietary operating systems.
Microsoft Windows
Microsoft Windows is the collective brand name of several operating systems made by Microsoft which, as of 2015, are installed on PCs built by HP, Dell and Lenovo, the three remaining high volume manufacturers. Microsoft first introduced an operating environment named Windows in November 1985, as an add-on to MS-DOS and in response to the growing interest in graphical user interfaces (GUIs) generated by Apple's 1984 introduction of the [Macintosh. As of January 2017, the most recent client and server versions of Windows are Windows 10 and Windows Server 2016. Windows is by far the most common operating system on desktop and laptop PCs.
macOS
macOS (formerly OS X) is a line of operating systems developed, marketed and sold by Apple Inc. macOS is the successor to the original Mac OS, which had been Apple's primary operating system since 1984. macOS is a Unix-based graphical operating system, and Snow Leopard, Leopard, Lion, Mountain Lion, Mavericks, Yosemite, El Capitan and Sierra are its version code-names. The most recent version of macOS is code-named macOS Mojave. The macOS is based upon the Mach kernel. Certain parts from FreeBSD's and NetBSD's implementation of Unix were incorporated in NeXTSTEP, the core of Mac OS X. Most libraries and utilities are from FreeBSD, but some are derived from NetBSD. For future development, OS X has adopted FreeBSD as a reference code base for BSD technology. Work is ongoing to more closely synchronize all BSD tools and libraries with the FreeBSD-stable branch.
FreeBSD
FreeBSD is an operating system for a variety of platforms which focuses on features, speed, and stability. It is derived from 4.4BSD, the version of UNIX
developed at the University of California, Berkeley. It is developed
and maintained by a large community. While FreeBSD is popular as a
server for its performance and stability, it is also suited for
day-to-day use as a desktop. With over 30,000 applications available as
FreeBSD packages or ports, it is easy to build a customized desktop that
runs a wide variety of desktop applications. Some specific projects in
this category include improved FUSE support, Linuxulator improvements,
Intel graphics support, WiFi improvements, 802.11ac support, and driver
updates, and work to finish and integrate the packaged base effort.
Usually, many people consider servers when thinking of FreeBSD, but
FreeBSD also continues to run well on client devices (laptops and
desktops). This allows developers to test their work as well as the work
of others on an ongoing basis under a variety of usage conditions. In
addition, technologies often transition from being perceived as relevant
only to client devices to being a critical requirement for servers –
for example, power management. It has OpenZFS integration which is an open source file system and logical volume manager originally designed by Sun Microsystems. There is also two downstream projects known as TrueOS, which is a bit "cutting-edge FreeBSD", and Project Trident, which is a desktop-focused operating system based on TrueOS.
Linux
Linux is a family of Unix-like computer operating systems. Linux is one of the most prominent examples of free software and open source development: typically all underlying source code can be freely modified, used, and redistributed by anyone. The name "Linux" refers to the Linux kernel, started in 1991 by Linus Torvalds. The system's utilities and libraries usually come from the GNU operating system, announced in 1983 by Richard Stallman. The GNU contribution is the basis for the alternative name GNU/Linux. However, there are other user land such as BusyBox also available via distros such as Alpine Linux.
Known for its use in servers, with the LAMP application stack as one of prominent examples, Linux is supported by corporations such as Dell, Hewlett-Packard, IBM, Novell, Oracle Corporation, Red Hat, Canonical Ltd. and Sun Microsystems. It is used as an operating system for a wide variety of computer hardware, including desktop computers, netbooks, supercomputers, video game systems such as the Steam Machine or PlayStation 3 (until this option was removed remotely by Sony in 2010), several arcade games, and embedded devices such as mobile phones, portable media players, routers, and stage lighting systems.
Applications
A screenshot of GIMP, which is a raster graphics editor.
Generally, a computer user uses application software to carry out a specific task. System software supports applications
and provides common services such as memory management, network
connectivity and device drivers, all of which may be used by
applications but are not directly of interest to the end user. A
simplified analogy
in the world of hardware would be the relationship of an electric light
bulb (an application) to an electric power generation plant (a system):
the power plant merely generates electricity, not itself of any real
use until harnessed to an application like the electric light that
performs a service that benefits the user.
Typical examples of software applications are word processors, spreadsheets, and media players. Multiple applications bundled together as a package are sometimes referred to as an application suite. Microsoft Office and LibreOffice, which bundle together a word processor, a spreadsheet, and several other discrete applications, are typical examples. The separate applications in a suite usually have a user interface
that has some commonality making it easier for the user to learn and
use each application. Often, they may have some capability to interact
with each other in ways beneficial to the user; for example, a
spreadsheet might be able to be embedded in a word processor document
even though it had been created in the separate spreadsheet application.
End-user development
tailors systems to meet the user's specific needs. User-written
software include spreadsheet templates, word processor macros,
scientific simulations, graphics and animation scripts; even email
filters are a kind of user software. Users create this software
themselves and often overlook how important it is.
Gaming
PC gaming is popular among the high-end PC market. According to an April 2014 market analysis, Gaming platforms like Steam (software), Uplay, Origin, and GOG.com (as well as competitive e Sports titles like League of Legends) are largely responsible for PC systems overtaking console revenue in 2013.
Sales
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Personal computers worldwide in million distinguished by developed and developing world
In 2001, 125 million personal computers were shipped in comparison to 48,000 in 1977. More than 500 million personal computers were in use in 2002 and one billion
personal computers had been sold worldwide from the mid-1970s up to
this time. Of the latter figure, 75% were professional or work related,
while the rest were sold for personal or home use. About 81.5% of
personal computers shipped had been desktop computers, 16.4% laptops and 2.1% servers.
The United States had received 38.8% (394 million) of the computers
shipped, Europe 25% and 11.7% had gone to the Asia-Pacific region, the
fastest-growing market as of 2002. The second billion was expected to be
sold by 2008. Almost half of all households in Western Europe had a personal computer and a computer could be found in 40% of homes in United Kingdom, compared with only 13% in 1985.
The global personal computer shipments were 350.9 million units in 2010,
308.3 million units in 2009
and 302.2 million units in 2008.
The shipments were 264 million units in the year 2007, according to iSuppli, up 11.2% from 239 million in 2006. In 2004, the global shipments were 183 million units, an 11.6% increase over 2003. In 2003, 152.6 million computers were shipped, at an estimated value of $175 billion. In 2002, 136.7 million PCs were shipped, at an estimated value of $175 billion. In 2000, 140.2 million personal computers were shipped, at an estimated value of $226 billion.
Worldwide shipments of personal computers surpassed the 100-million
mark in 1999, growing to 113.5 million units from 93.3 million units in
1998. In 1999, Asia had 14.1 million units shipped.
As of June 2008, the number of personal computers in use worldwide hit one billion, while another billion is expected to be reached by 2014. Mature markets like the United States, Western Europe and Japan accounted for 58% of the worldwide installed PCs. The emerging markets
were expected to double their installed PCs by 2012 and to take 70% of
the second billion PCs. About 180 million computers (16% of the existing
installed base) were expected to be replaced and 35 million to be
dumped into landfill in 2008. The whole installed base grew 12%
annually.
Based on International Data Corporation
(IDC) data for Q2 2011, for the first time China surpassed US in PC
shipments by 18.5 million and 17.7 million respectively. This trend
reflects the rising of emerging markets as well as the relative
stagnation of mature regions.
In the developed world,
there has been a vendor tradition to keep adding functions to maintain
high prices of personal computers. However, since the introduction of
the One Laptop per Child foundation and its low-cost XO-1
laptop, the computing industry started to pursue the price too.
Although introduced only one year earlier, there were 14 million netbooks sold in 2008.
Besides the regular computer manufacturers, companies making especially
rugged versions of computers have sprung up, offering alternatives for
people operating their machines in extreme weather or environments.
In 2011, Deloitte consulting firm predicted that, smartphones and tablet computers as computing devices would surpass the PCs sales
(as has happened since 2012). As of 2013, worldwide sales of PCs had
begun to fall as many consumers moved to tablets and smartphones for
gifts and personal use. Sales of 90.3 million units in the 4th quarter
of 2012 represented a 4.9% decline from sales in the 4th quarter of
2011.
Global PC sales fell sharply in the first quarter of 2013, according to
IDC data. The 14% year-over-year decline was the largest on record
since the firm began tracking in 1994, and double what analysts had been
expecting. The decline of Q2 2013 PC shipments marked the fifth straight quarter of falling sales.
"This is horrific news for PCs," remarked an analyst. "It's all about
mobile computing now. We have definitely reached the tipping point." Data from Gartner showed a similar decline for the same time period. China's Lenovo Group
bucked the general trend as strong sales to first time buyers in the
developing world allowed the company's sales to stay flat overall. Windows 8,
which was designed to look similar to tablet/smartphone software, was
cited as a contributing factor in the decline of new PC sales.
"Unfortunately, it seems clear that the Windows 8 launch not only didn’t
provide a positive boost to the PC market, but appears to have slowed
the market," said IDC Vice President Bob O’Donnell.
In August 2013, Credit Suisse published research findings that
attributed around 75% of the operating profit share of the PC industry
to Microsoft (operating system) and Intel (semiconductors).
According to IDC, in 2013 PC shipments dropped by 9.8% as the greatest
drop-ever in line with consumers trends to use mobile devices.
In the second quarter of 2018, PC sales grew for the first time
since the first quarter of 2012. According to research firm Gartner, the
growth mainly came from the business market while the consumer market
experienced decline.
Average selling price
Selling
prices of personal computers steadily declined due to lower costs of
production and manufacture, while the capabilities of computers
increased. In 1975, an Altair kit sold for only around US$400, but
required customers to solder components into circuit boards; peripherals
required to interact with the system in alphanumeric form instead of
blinking lights would add another $2,000, and the resultant system was
only of use to hobbyists.
At their introduction in 1981, the US$1,795 price of the Osborne 1 and its competitor Kaypro was considered an attractive price point; these systems had text-only displays and only floppy disks for storage. By 1982, Michael Dell
observed that a personal computer system selling at retail for about
$3,000 US was made of components that cost the dealer about $600;
typical gross margin on a computer unit was around $1,000. The total value of personal computer purchases in the US in 1983 was about $4 billion, comparable to total sales of pet food. By late 1998, the average selling price of personal computer systems in the United States had dropped below $1,000.
For Microsoft Windows systems, the average selling price (ASP) showed a decline in 2008/2009, possibly due to low-cost netbooks, drawing $569 for desktop computers and $689 for laptops
at U.S. retail in August 2008. In 2009, ASP had further fallen to $533
for desktops and to $602 for notebooks by January and to $540 and $560
in February. According to research firm NPD, the average selling price of all Windows portable PCs has fallen from $659 in October 2008 to $519 in October 2009.[92]
Environmental impact
External costs of environmental impact are not fully included in the
selling price of personal computers. This impact differs between desktop
computers and laptops.
Personal computers have become a large contributor to the 50
million tons of discarded electronic waste that is being generated
annually, according to the United Nations Environment Programme. To address the electronic waste issue affecting developing countries and the environment, extended producer responsibility (EPR) acts have been implemented in various countries and states. Organizations, such as the Silicon Valley Toxics Coalition, Basel Action Network, Toxics Link India, SCOPE, and Greenpeace
have contributed to these efforts. In the absence of comprehensive
national legislation or regulation on the export and import of
electronic waste, the Silicon Valley Toxics Coalition
and BAN (Basel Action Network) teamed up with 32 electronic recyclers
in the US and Canada to create an e-steward program for the orderly
disposal of manufacturers' and customers' electronic waste. The Silicon
Valley Toxics Coalition founded the Electronics TakeBack Coalition, a
coalition that advocates for the production of environmentally friendly
products. The TakeBack Coalition works with policy makers, recyclers,
and smart businesses to get manufacturers to take full responsibility of
their products. There are organizations opposing EPR regulation, such
as the Reason Foundation.
They see flaws in two principal tenets of EPR: First EPR relies on the
idea that if the manufacturers have to pay for environmental harm, they
will adapt their practices. Second EPR assumes the current design
practices are environmentally inefficient. The Reason Foundation claims
that manufacturers naturally move toward reduced material and energy
use.
