Peripherals devices

In addition, hardware can include external components of a computer system. The following are either standard or very common.

Includes various input and output devices, usually external to the computer system

Input:

* Text input devices
o Keyboard - a device to input text and characters by depressing buttons (referred to as keys), similar to a typewriter. The most common English-language key layout is the QWERTY layout.
* Pointing devices
o Mouse - a pointing device that detects two dimensional motion relative to its supporting surface.
o Trackball - a pointing device consisting of an exposed portruding ball housed in a socket that detects rotation about two axes.
* Gaming devices
o Joystick - a general control device that consists of a handheld stick that pivots around one end, to detect angles in two or three dimensions.
o Gamepad - a general game controller held in the hand that relies on the digits (especially thumbs) to provide input.
o Game controller - a specific type of controller specialized for certain gaming purposes.
* Image, Video input devices
o Image scanner - a device that provides input by analyzing images, printed text, handwriting, or an object.
o Webcam - a low resolution video camera used to provide visual input that can be easily transferred over the internet.
* Audio input devices
o Microphone - an acoustic sensor that provides input by converting sound into an electrical signal

Output:

* Image, Video output devices
o Printer - a peripheral device that produces a hard (usually paper) copy of a document.
o Monitor - device that displays a video signal, similar to a television, to provide the user with information and an interface with which to interact.
* Audio output devices
o Speakers - a device that converts analog audio signals into the equivalent air vibrations in order to make audible sound.
o Headset - a device similar in functionality to computer speakers used mainly to not disturb others nearby.

various devices

Internal storage:
Hardware that keeps data inside the computer for later use and remains persistent even when the computer has no power.

* Hard disk - for medium-term storage of data.
* Solid state drive - a device emulating a hard disk, but containing no moving parts.
* Disk array controller - a device to manage several hard disks, to achieve performance or reliability improvement.

Sound card:
Enables the computer to output sound to audio devices, as well as accept input from a microphone. Most modern computers have sound cards built-in to the motherboard, though it is common for a user to install a separate sound card as an upgrade.

Networking:

Connects the computer to the Internet and/or other computers.

* Modem - for dial-up connections
* Network card - for DSL/Cable internet, and/or connecting to other computers.
* Direct Cable Connection - Use of a null modem, connecting two computers together using their serial ports or a Laplink Cable, connecting two computers together with their parallel ports.

controllers

Storage controllers:

Controllers for hard disk, CD-ROM and other drives like internal Zip and Jaz conventionally for a PC are IDE/ATA; the controllers sit directly on the motherboard (on-board) or on expansion cards, such as a Disk array controller. IDE is usually integrated, unlike SCSI which is found in most servers. The floppy drive interface is a legacy MFM interface which is now slowly disappearing. All these interfaces are gradually being phased out to be replaced by SATA and SAS.

Video display controller:

Produces the output for the computer display. This will either be built into the motherboard or attached in its own separate slot (PCI, PCI-E or AGP), in the form of a Graphics Card.

Removable media devices:

* CD - the most common type of removable media, inexpensive but has a short life-span.
o CD-ROM Drive - a device used for reading data from a CD.
o CD Writer - a device used for both reading and writing data to and from a CD.
* DVD - a popular type of removable media that is the same dimensions as a CD but stores up to 6 times as much information. It is the most common way of transferring digital video.
o DVD-ROM Drive - a device used for reading data from a DVD.
o DVD Writer - a device used for both reading and writing data to and from a DVD.
o DVD-RAM Drive - a device used for rapid writing and reading of data from a special type of DVD.
* Blu-ray - a high-density optical disc format for the storage of digital information, including high-definition video. Currently a rival of HD DVD.
o BD-ROM Drive - a device used for reading data from a Blu-ray disc.
o BD Writer - a device used for both reading and writing data to and from a Blu-ray disc.
* HD DVD - a high-density optical disc format and successor to the standard DVD. Currently a rival of Blu-ray
* Floppy disk - an outdated storage device consisting of a thin disk of a flexible magnetic storage medium.
* Zip drive - an outdated medium-capacity removable disk storage system, first introduced by Iomega in 1994.
* USB flash drive - a flash memory data storage device integrated with a USB interface, typically small, lightweight, removable and rewritable.
* Tape drive - a device that reads and writes data on a magnetic tape, usually used for long term storage.

mother board

Motherboard:

The motherboard is the "heart" of the computer, through which all other components interface.

* Central processing unit (CPU) - Performs most of the calculations which enable a computer to function, sometimes referred to as the "brain" of the computer.
o Computer fan - Used to lower the temperature of the computer; a fan is almost always attached to the CPU, and the computer case will generally have several fans to maintain a constant airflow. Liquid cooling can also be used to cool a computer, though it focuses more on individual parts rather than the overall temperature inside the chassis.
* Random Access Memory (RAM) - Fast-access memory that is cleared when the computer is powered-down. RAM attaches directly to the motherboard, and is used to store programs that are currently running.
* Firmware is loaded from the Read only memory ROM run from the Basic Input-Output System (BIOS) or in newer systems Extensible Firmware Interface (EFI) compliant
* Internal Buses - Connections to various internal components.
o PCI
o PCI-E
o USB
o HyperTransport
o CSI (expected in 2008)
o AGP (being phased out)
o VLB (outdated)
o ISA (outdated)
o EISA (outdated)
o MCA (outdated)
* External Bus Controllers - used to connect to external peripherals, such as printers and input devices. These ports may also be based upon expansion cards, attached to the internal buses.
o parallel port
o serial port
o USB
o firewire
o SCSI (On Servers and older machines)
o PS/2 (For mice and keyboards, being phased out and replaced by USB.)

Power supply:

A case that holds a transformer, voltage control, and (usually) a cooling fan, and supplies power to run the rest of the computer.