Computer hardware are the physical parts or components of a computer,
such as the monitor, keyboard, computer data storage, graphic card,
sound card and motherboard. By contrast, software is instructions
that can be stored and ran by hardware.
Hardware is directed by the software to execute any command or
instruction. A combination of hardware and software forms a usable
1 Von Neumann architecture
3 Different systems
3.1 Personal computer
3.1.2 Power supply
3.1.4 Expansion cards
3.1.5 Storage devices
184.108.40.206 Fixed media
220.127.116.11 Removable media
Input and output
Input and output peripherals
18.104.22.168 Output device
3.2 Mainframe computer
3.3 Departmental computing
4 Hardware upgrade
5.1 Toxic computer components
5.2 Environmental effects
5.3 National services
6 See also
8 External links
Von Neumann architecture
Main article: Von Neumann architecture
Von Neumann architecture
Von Neumann architecture scheme
The template for all modern computers is the Von Neumann architecture,
detailed in a 1945 paper by Hungarian mathematician John von Neumann.
This describes a design architecture for an electronic digital
computer with subdivisions of a processing unit consisting of an
arithmetic logic unit and processor registers, a control unit
containing an instruction register and program counter, a memory to
store both data and instructions, external mass storage, and input and
output mechanisms. The meaning of the term has evolved to mean a
stored-program computer in which an instruction fetch and a data
operation cannot occur at the same time because they share a common
bus. This is referred to as the
Von Neumann bottleneck
Von Neumann bottleneck and often
limits the performance of the system.
For the third consecutive year, U.S. business-to-business channel
sales (sales through distributors and commercial resellers) increased,
ending 2013 up nearly 6 percent at $61.7 billion. The impressive
growth was the fastest sales increase since the end of the recession.
Sales growth accelerated in the second half of the year peaking in
fourth quarter with a 6.9 percent increase over the fourth quarter of
There are a number of different types of computer system in use today.
Basic hardware components of a modern personal computer, including a
monitor, a motherboard, a CPU, a RAM, two expansion cards, a power
supply, an optical disc drive, a hard disk drive, a keyboard and a
Inside a custom-built computer: power supply at the bottom has its own
The personal computer, also known as the PC, is one of the most common
types of computer due to its versatility and relatively low price.
Laptops are generally very similar, although they may use lower-power
or reduced size components, thus lower performance.
The computer case encloses most of the components of the system. It
provides mechanical support and protection for internal elements such
as the motherboard, disk drives, and power supplies, and controls and
directs the flow of cooling air over internal components. The case is
also part of the system to control electromagnetic interference
radiated by the computer, and protects internal parts from
electrostatic discharge. Large tower cases provide extra internal
space for multiple disk drives or other peripherals and usually stand
on the floor, while desktop cases provide less expansion room.
All-in-one style designs from Apple, namely the iMac, and similar
types, include a video display built into the same case. Portable and
laptop computers require cases that provide impact protection for the
unit. A current development in laptop computers is a detachable
keyboard, which allows the system to be configured as a touch-screen
tablet. Hobbyists may decorate the cases with colored lights, paint,
or other features, in an activity called case modding.
Main article: Power supply unit (computer)
A power supply unit (PSU) converts alternating current (AC) electric
power to low-voltage DC power for the internal components of the
computer. Laptops are capable of running from a built-in battery,
normally for a period of hours.
Main article: Motherboard
The motherboard is the main component of a computer. It is a board
with integrated circuitry that connects the other parts of the
computer including the CPU, the RAM, the disk drives (CD, DVD, hard
disk, or any others) as well as any peripherals connected via the
ports or the expansion slots.
Components directly attached to or to part of the motherboard include:
CPU (central processing unit), which performs most of the
calculations which enable a computer to function, and is sometimes
referred to as the brain of the computer. It is usually cooled by a
heatsink and fan, or water-cooling system. Most newer CPUs include an
on-die Graphics Processing Unit (GPU). The clock speed of CPUs governs
how fast it executes instructions, and is measured in GHz; typical
values lie between 1 GHz and 5 GHz. Many modern computers
have the option to overclock the
CPU which enhances performance at the
expense of greater thermal output and thus a need for improved
The chipset, which includes the north bridge, mediates communication
CPU and the other components of the system, including main
Random-access memory (RAM), which stores the code and data that are
being actively accessed by the CPU. For example, when a web browser is
opened on the computer it takes up memory; this is stored in the RAM
until the web browser is closed.
RAM usually comes on DIMMs in the
sizes 2GB, 4GB, and 8GB, but can be much larger.
Read-only memory (ROM), which stores the
BIOS that runs when the
computer is powered on or otherwise begins execution, a process known
as Bootstrapping, or "booting" or "booting up". The
BIOS (Basic Input
Output System) includes boot firmware and power management firmware.
Newer motherboards use Unified Extensible
Firmware Interface (UEFI)
instead of BIOS.
Buses that connect the
CPU to various internal components and to
expand cards for graphics and sound.
The CMOS battery, which powers the memory for date and time in the
BIOS chip. This battery is generally a watch battery.
The video card (also known as the graphics card), which processes
computer graphics. More powerful graphics cards are better suited to
handle strenuous tasks, such as playing intensive video games.
Main article: Expansion card
An expansion card in computing is a printed circuit board that can be
inserted into an expansion slot of a computer motherboard or backplane
to add functionality to a computer system via the expansion bus.
Expansions cards can be used to obtain or expand on features not
offered by the motherboard.
Computer data storage
A storage device is any computing hardware and digital media that is
used for storing, porting and extracting data files and objects. It
can hold and store information both temporarily and permanently, and
can be internal or external to a computer, server or any similar
computing device. Data storage is a core function and fundamental
component of computers.
Data is stored by a computer using a variety of media. Hard disk
drives are found in virtually all older computers, due to their high
capacity and low cost, but solid-state drives are faster and more
power efficient, although currently more expensive than hard drives in
terms of dollar per gigabyte, so are often found in personal
computers built post-2007. Some systems may use a disk array
controller for greater performance or reliability.
To transfer data between computers, a
USB flash drive
USB flash drive or optical disc
may be used. Their usefulness depends on being readable by other
systems; the majority of machines have an optical disk drive, and
virtually all have at least one
Input and output
Input and output peripherals
Main article: Peripheral
Input and output
Input and output devices are typically housed externally to the main
computer chassis. The following are either standard or very common to
many computer systems.
Input devices allow the user to enter information into the system, or
control its operation. Most personal computers have a mouse and
keyboard, but laptop systems typically use a touchpad instead of a
mouse. Other input devices include webcams, microphones, joysticks,
and image scanners.
Output devices display information in a human readable form. Such
devices could include printers, speakers, monitors or a Braille
Main article: Mainframe Computer
A mainframe computer is a much larger computer that typically fills a
room and may cost many hundreds or thousands of times as much as a
personal computer. They are designed to perform large numbers of
calculations for governments and large enterprises.
IBM System z9
IBM System z9 mainframe
Main article: Minicomputer
In the 1960s and 1970s, more and more departments started to use
cheaper and dedicated systems for specific purposes like process
control and laboratory automation.
Main article: Supercomputer
A supercomputer is superficially similar to a mainframe, but is
instead intended for extremely demanding computational tasks. As of
June 2016[update], the fastest supercomputer in the world is the
Sunway TaihuLight, in Jiangsu, China.
The term supercomputer does not refer to a specific technology. Rather
it indicates the fastest computations available at any given time. In
mid 2011, the fastest supercomputers boasted speeds exceeding one
petaflop, or 1 quadrillion (10^15 or 1,000 trillion) floating point
operations per second. Super computers are fast but extremely costly
so they are generally used by large organizations to execute
computationally demanding tasks involving large data sets. Super
computers typically run military and scientific applications. Although
they cost millions of dollars, they are also being used for commercial
applications where huge amounts of data must be analyzed. For example,
large banks employ supercomputers to calculate the risks and returns
of various investment strategies, and healthcare organizations use
them to analyze giant databases of patient data to determine optimal
treatments for various diseases and problems incurring to the country.
When using computer hardware, an upgrade means adding new hardware to
a computer that improves its performance, adds capacity or new
features. For example, a user could perform a hardware upgrade to
replace the hard drive with a
SSD to get a boost in performance or
increase the amount of files that may be stored. Also, the user could
RAM so the computer may run more smoothly. The user could
USB 3.0 expansion card in order to fully use
USB 3.0 devices, or
could upgrade the
GPU for extra rendering power. Performing such
hardware upgrades may be necessary for older computers to meet a
programs' system requirements.
Because computer parts contain hazardous materials, there is a growing
movement to recycle old and outdated parts.
contain dangerous chemicals such as: lead, mercury, nickel, and
cadmium. According to the EPA these e-wastes have a harmful effect on
the environment unless they are disposed of properly. Making hardware
requires energy, and recycling parts will reduce air pollution, water
pollution, as well as greenhouse gas emissions. Disposing
unauthorized computer equipment is in fact illegal. Legislation makes
it mandatory to recycle computers through the government approved
Recycling a computer can be made easier by taking out
certain reusable parts. For example, the RAM,
DVD drive, the graphics
card, hard drive or SSD, and other similar removable parts can be
Toxic computer components
The central processing unit contains many toxic materials. It contains
lead and chromium in the metal plates. Resistors, semi-conductors,
infrared detectors, stabilizers, cables, and wires contain cadmium.
The circuit boards in a computer contain mercury, and chromium.
When these types of materials, and chemicals are disposed improperly
will become hazardous for the environment.
According to the
United States Environmental Protection Agency
United States Environmental Protection Agency only
around 15% of the e-waste actually is recycled. When e-waste
byproducts leach into ground water are burned or get mishandled during
recycling it causes harm. Health problems associated with such toxins
include impaired mental development, cancer, and damage to the lungs,
liver, and kidneys. That's why even wires have to be recycled.
Different companies have different techniques to recycle a wire. The
most popular one is the grinder that separates the copper wires form
the plastic/rubber casing. When the processes is done there are two
different piles left; one containing the copper powder, and the other
containing plastic/rubber pieces.
Computer monitors, mice, and
keyboards all have a similar way of being recycled. For example, first
each of the parts are taken apart then all of the inner parts get
separated and placed into its own bin.
Recycling a computer is made easier by a few of the national services,
Dell and Apple. Both companies will take back the computer of
their make or any other make. Otherwise a computer can be donated to
Computer Aid International which is an organization that recycles and
refurbishes old computers for hospitals, schools, universities,
Information technology portal
Glossary of computer hardware terms
History of computing hardware
List of computer hardware manufacturers
Open-source computing hardware
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Media related to
Computer hardware at Wikimedia Commons
Learning materials related to
Computer hardware at Wikiversity
Basic computer components
Refreshable braille display
Refreshable braille display
USB flash drive
Central processing unit
Central processing unit (CPU)
SSD / SSHD
Network interface controller
Random-access memory (RAM)
FireWire (IEEE 1394)
HDMI / DVI / VGA
Major fields of computer science
Note: This template roughly follows the 2012 ACM Computing
Printed circuit board
Electronic design automation
Network performance evaluation
Integrated development environment
Software configuration management
Software development process
Theory of computation
Model of computation
Computational complexity theory
Analysis of algorithms
Database management system
Information storage systems
Enterprise information system
Social information systems
Geographic information system
Decision support system
Process control system
Multimedia information system
World Wide Web
Intrusion detection system
Natural language processing
Knowledge representation and reasoning
Automated planning and scheduling
Philosophy of artificial intelligence
Distributed artificial intelligence
Graphics processing unit
Computational social science