Four Basic Parts of a Computer

By Allen Bethea

Desktop computers provide easy access to the parts within.
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Today's thin, light and stylish notebook and tablet PCs mask the incredibly sophisticated technology that powers them. Despite their beauty and polish, beneath the surface lies the same basic technology used in hardworking, plain and featureless mainframe or server computers. Whether they are used to browse the Internet, run business applications or perform complex scientific calculations, all computers consist of four basic parts: the CPU, motherboard, data input and data output devices.


The CPU, or central processing unit, provides most of a computer's intelligence. CPUs perform arithmetic calculations, compare data and move information from one memory location to another under the direction of a program. Computer programs are instructions given to the CPU to perform a task. CPUs can execute program instructions one after another or they can jump from one part of the program to another based upon the results of previous calculations. CPUs rely on memory locations called registers to hold data to be processed or program instructions. In addition, some CPUs have a special cache of high-speed memory used to hold a copy of frequently used data from the computer's main memory close at hand for fast access.


By itself, the CPU is no more useful than a car engine without a chassis, transmission or wheels. The motherboard provides the thoroughfare for the transfer of information throughout the computer. The computer's main memory or system RAM, network interfaces, USB ports, video inputs, storage device interfaces, BIOS and system clock are either built into or connected to the motherboard by a slot .

Input Devices

Your computer gets information to process from several sources. Input devices like your keyboard, mouse, trackball and touch pad feed information and instructions to the applications running on your computer. Other sources of data include hard disks, CD-ROM, DVD-ROM and USB thumb drives. Information also streams into a computer from network connections like the Internet.

Output Devices

Output devices are needed to temporarily or permanently display, broadcast or record the work done by your computer. Computer speakers and monitors are output devices. Many computers have storage devices like hard drives, SSD drives, thumb drives or CD burners which provide a more permanent form of data output and storage. Other output devices like printers and projectors are connected the computer through ports.