Computer hardware

From Wikipedia, the free encyclopedia

Computer hardware is the physical part of a computer, including the 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 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.

[edit] Personal computer hardware

A typical personal computer consists of a case or chassis in desktop or tower shape and the following parts: Image:ASRock K7VT4A Pro Mainboard.jpg

Motherboard or system board with slots for expansion cards and holding parts including:
- Central processing unit (CPU)
- Random Access Memory (RAM) - for program execution and short term data storage, so the computer does not have to take the time to access the hard drive to find something. More RAM can contribute to a faster PC. RAM is normally removable by being in slots on the motherboard.
- Basic Input-Output System (BIOS) or Extensible Firmware Interface (EFI) in newer computers
- Buses :
  - PCI
  - PCI-E
  - USB
  - HyperTransport
  - CSI (expected in 2008)
  - AGP (being phased out)
  - VLB (outdated)
  - ISA (outdated)
  - EISA (outdated)
Power supply - a case that holds a transformer, voltage control, and (usually) a cooling fan
Storage controllers of IDE, SATA, SCSI or other type, that control hard disk, floppy disk, CD-ROM and other drives; the controllers sit directly on the motherboard (on-board) or on expansion cards
Video display controller that produces the output for the computer display
Computer bus controllers (parallel, serial, USB, FireWire) to connect the computer to external peripheral devices such as printers or scanners
Some type of a removable media writer:
- CD - the most common type of removable media, cheap but fragile.
  - CD-ROM Drive
  - CD Writer
- DVD
- Floppy disk
- Zip drive
- USB Flash Drive
- Tape drive - mainly for backup and long-term storage
Internal storage - keeps data inside the computer for later use.
- Hard disk - for medium-term storage of data.
- Disk array controller
Sound card - translates signals from the system board into analog voltage levels, and has terminals to plug in speakers.
Networking - to connect 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.
Other peripherals

In addition, hardware can include external components of a computer system. The following are either standard or very common. Image:3-Tastenmaus Microsoft.jpg

Input or Input devices
- Text input devices
  - Keyboard
- Pointing devices
  - Mouse
  - Trackball
- Gaming devices
- Image, Video input devices
  - Image scanner
  - Webcam
- Audio input devices
  - Microphone
Output or Output devices
- Image, Video output devices
  - Printer Peripheral device that produces a hard copy. (Inkjet, Laser)
  - Monitor Device that takes signals and displays them. (CRT, LCD)
- Audio output devices
  - Speakers A device that converts analog audio signals into the equivalent air vibrations in order to make audible sound.
  - headset A device similar in functionality to that of a regular telephone handset but is worn on the head to keep the hands free.