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System unit |
The system unit is the heart of your computer system. It's usually a rectangular box which sits on or under your desk and contains these components:
The central processing unit (CPU), sometimes called the microprocessor or ‘chip’, which is your computer’s brain.
Memory, called random access memory (RAM), which is used by the CPU while it’s working. This memory is erased when the computer is turned off.
A hard disk drive, which stores all your programs, documents, music and video files. This information is kept when your computer is turned off.
A CD or DVD drive. A CD drive reads music and data CDs. A DVD drive does everything a CD drive can, but also reads data and movie DVDs. Many modern computers can also record information onto CDs and DVDs. This is called ‘writing’ or ‘burning’.
All the other parts of your computer system, called ‘devices’ or ‘peripherals’ connect into the system unit using cables that plug into sockets called ‘ports’.
The monitor is your computer’s screen. It’s just like a television, but doesn’t have a TV tuner built in to it.
Most modern computers have LCD (liquid crystal display) monitors because they are much slimmer and lighter than the older CRT (cathode ray tube) monitors, but both can give excellent results.
A mouse is a pointing device used to select and move items on your computer screen. It’s called a mouse because it looks like one, with an oval body and a tail-like connecting wire, although many newer mice are wireless.
A mouse usually has two or more buttons with a wheel in between them, which allows you to scroll through pages of information.
A keyboard is used to type text on your computer. Like the keyboard on a typewriter, it has keys for letters and numbers. It also has navigation that help you move around the screen and several keys that perform special functions.
A printer prints text and images from your computer screen onto paper.
The two main types of printers are inkjet printers and laser printers.
Inkjet printers are the most popular printers for the home because they are cheap to buy. They can print in full colour and can produce high-quality photographs especially when used with special paper. However, they can have quite high running costs, and are therefore not usually suitable for high volumes of printing.
Laser printers are faster, cheaper to run and well-suited to heavier use in an office. Models are available which print in plain black or in colour, although colour laser printers are more expensive to buy and run.
Speakers allow you to listen to music and on-line videos or DVDs. They are sometimes built into your system unit or laptop but higher quality speakers usually connect to your system unit with cables.
A modem is a small box that connects your computer to the internet through a telephone line or cable.
A webcam is a small video camera that plugs into your computer and allows you to broadcast real-time video over the internet. This is useful for making video calls, using instant messaging and creating podcasts.
Many new laptops have webcams built in and they are commonly available as add-on devices for desktop computers.