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Computer Parts and Peripherals

Computer parts

Input devices

  • Keyboard – one of the two main input devices (along with a mouse). Computers do not have to have these if they are not used by a human.

  • Mouse – one of the two main input devices (along with a keyboard). Computers do not have to have these if they are not used by a human.

  • Trackpad (touchpad) or touch screen – a panel which can be touched to indicate pointing, as alternative to using a mouse. Some touch screens on smartphones can accept 10 touch points at once.

Output devices

  • Screen or monitor or display – the main output device, although a touch screen can also be an input device at the same time. Computers do not have to have a screen if they are not going to be used by a human.

  • Sound card and speakers – an output device for producing sound. Most computers these days have their sound incorporated on their motherboard so do not have a sound card (an expansion card which can do the sound control work). Most PCs need external speakers, whereas Macs have speakers built in.


  • CPU – see Computer Acronyms. The main brain of a computer, where most of the "thinking" is done. It accepts both instructions and data, and issues processed data and sometimes instructions for other parts of the computer.

  • Graphics card or video card or GPU – most computers these days have graphics controllers on the motherboard but for gaming and other graphics-intensive activities a separate graphics controller on an expansion card can be used to process their graphics for them. Graphics cards provide a huge amount of computing for three dimensional environments, used especially in games.


  • Memory (RAM) – the main short term storage of a computer is RAM (see Computer Acronyms and Abbreviation). The first common home computers (eg, ZX81) had 1KB of RAM. My current Mac has 8GB of RAM (8 million times as much). Computers also have a small amount of ROM as well, which tells the computer how to start up. Everything in RAM is lost if the power is interrupted or turned off, while ROM keeps its contents.

  • Hard disk drive – the main long term storage. One or more hard disks are permanently mounted inside a computer. A hard disk can also be external, and connected with Firewire or USB.

  • Optical drive – as well as being for storage, an optical disk drive can also be thought of as an input device, and is especially useful for digitising music files or installing new programmes. An optical drive can also be an output device if the optical drive can write to optical media (eg, CD-R, DVD-R, DVD+RW, etc). These are not as common on new computers these days.


  • Broadband router – used to connect a home computer to the Internet.

  • Modem – see Computer Acronyms and Abbreviations. Used to connect the computer to a telephone line. Not used a whole lot these days.

  • Network connection – for connecting to a network. This is often an ethernet connector, which can be on the motherboard or on an expansion card.

  • WiFi – a wireless network commonly used for laptops and other portable devices to transport data. Particularly used for Internet access.

  • Bluetooth – a low power low speed wireless communication method, used with peripherals (like wireless keyboards and mice) and sometimes for data communication between computers (like between a desktop and a cellphone). Note that Bluetooth has a capital letter.


  • Motherboard – the big circuit board on which is mounted the CPU, memory, and expansion cards, thus providing the physical mounting for all the other components. Without a motherboard the insides of computers would be very messy. It also provides the electrical connections so all the parts can communicate with each other as quickly and efficiently as posiible.

  • Expansion card – a card that plugs into the motherboard which expands the abilities of what the computer can do. Many computers have a graphics card or a WiFi card which both offer functionality the computer could not otherwise do. Storage is also available on expansion cards.

  • Power supply – converts mains power to 12 volt, 5 volt and 3.3 volt for the different power requirements of the computer's components. This is one of the most important components of a computer.

  • Heatsink – attached to a power-hungry integrated circuit like the CPU or GPU to help keep it cool. It helps remove heat from the hot item and typically has a large surface area with lots of fins so heat can be exchanged more easily with air passing over the fins.

  • Fan – used to blow air around a computer, especially over a heatsink, to keep things cool.

  • Bus – a subsystem that carries data or power around a computer. Examples are IDE (not used much any more; also called ATA) or SATA, or USB – see Computer Acronyms and Abbreviations.

Peripheral devices

Peripheral devices, or peripherals, are devices which are plugged into the outside of a computer to expand what a computer can do. The keyboard and mouse are peripherals. Optional peripherals include:

  • Camera – input device. Also called web cam. Some computers have a camera built in, but many computers do not.

  • Printer – output device for creating more permanent images that those appearing on the screen. 3D printing is also an option.

  • Scanner – input device for copying flat images.

  • USB missile launcher – an example of a device that can be plugged into a USB port, which can be controlled by someone using the computer.