Computer hardware is the physical part of a computer,(not to be confused with software which is not physical) 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").

Personal computer hardware

     A typical Personal computer consists of a case or chassis in desktop or tower shape and the following parts:

• Motherboard or system board with slots for expansion cards and holding parts
  • Central processing unit (CPU)
  • Computer fan - used to cool down the 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 the file(s) it requires. More RAM will normally contribute to a faster PC. RAM is almost always removable as it sits in slots in the motherboard, attached with small clips. The RAM slots are normally located next to the CPU socket.
• Basic Input-Output System (BIOS) or Extensible Firmware Interface (EFI) in some 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  • VLB (outdated)
  • ISA (outdated)
  • EISA (outdated)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. This will either be built into the motherboard or attached in its own separate slot (PCI, PCI-E or AGP), requiring a Graphics Card.
• 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
    • DVD-ROM Drive
    • DVD Writer
    • DVD-RAM Drive
  • BD
    • BD-ROM Drive
    • BD Writer
  • Floppy disk
  • Zip drive
  • USB flash drive AKA a Pen Drive, memory stick
  • 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.

• Input or Input devices
  • Text input devices
    • Keyboard
  • Pointing devices
    • Mouse
    • Trackball
  • Gaming devices
    • Joystick
    • Gamepad
    • Game controller
  • 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.

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