Computer Hardware Introduction

Computer hardware is the physical part of a computer ,
including its digital circuitry, as distinguished from the computer software that executes within the hardware. The hardware of a computer is infrequently changed, in comparison with software and hardware data, which are "soft" in the sense that they are readily created, modified or erased on the computer. Firmware is a special type of software that rarely, if ever, needs to be changed and so is stored on hardware devices such as read-only memory (ROM) where it is not readily changed (and is, therefore, "firm" rather than just "soft").

Most computer hardware is not seen by normal users. It is in embedded systems in automobiles, microwave ovens, electrocardiograph machines, compact disc players, and other devices. Personal computers, the computer hardware familiar to most people, form only a small minority of computers (about 0.2% of all new computers produced in 2003). See Market statistics.

MOTHERBOARD

* Motherboard - the "body" or mainframe 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o VLB (outdated)
* 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o parallel port (outdated)
o serial port (outdated)
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.)
o ISA (outdated)
o EISA (outdated)
o MCA (outdated)

Video display controller

Produces the output for the visual display unit. This will either be built into the motherboard or attached in its own separate slot (PCI, PCI-E, PCI-E 2.0, or AGP), in the form of a Graphics Card.


Computer storage

* CD (compact disc) - 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 (digital versatile disc) - 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.
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. It was a discontinued competitor to the Blu-ray format.
* 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.

Storage Devices

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 similar to hard disk, but containing no moving parts.
* Disk array controller - a device to manage several hard disks, to achieve performance or reliability impro