A computer is an electronic device that can store and process information. Computers help perform a variety of tasks such as receiving and sending messages to family and friends, making presentations, and maintaining records. Computers are also used in education, research, broadcasting news, making weather forecasts, and for various other business and recreational activities.
Parts of a Computer:
A computer has various parts, and each part performs a specific function. The following table describes the parts of a computer.
Part
Description
Input devices
Input devices are used to provide information to a computer, such as typing a letter or giving instructions to a computer. Some examples of input devices are as follows: Mouse: A standard mouse has a left and a right button. You use the left button to select items and provide instructions by clicking an active area on the screen. You use the right button to display commonly used menu items on the screen.Keyboard: A set of keys that resembles a keyboard on a typewriter. You use the keyboard to type text such as letters or numbers into the computer.Microphone: A device that you can use to talk to people in different parts of the world. You can record sound into a computer by using a microphone. You can also record your speech and let the computer convert it into text.Scanner: A device that is similar to a photocopy machine. You can use this device to transfer an exact copy of a photograph or document into a computer. A scanner reads a page and translates it into a digital format that a computer can read. For example, you can scan photographs of your family using a scanner.Webcam: A device that is similar to a video camera. It allows you to capture and send live pictures to other users. For example, a webcam allows your friends and family to see you when you are communicating with them.
Stylus: A pointing device, similar to a pen, used to make selections and enter information by tapping on a touch sensitive surface. For example, to enter information on a personal digital assistant (PDA), you use a stylus. A PDA is a lightweight, palmtop computer.Trackball: A pointing device that is an alternative to a mouse. A trackball consists of a ball that is rotated to move the pointer on a computer screen. You can use a trackball when you have limited desk space.
Output devices
You use output devices to get feedback from a computer after it performs a task. Some examples of output devices are as follows: Monitor: A device that is similar to a television. It is used to display information in visual form, using text and graphics.Printer: A device that you use to transfer text and images from a computer to a paper or to another medium, such as a transparency film. You can use a printer to create a paper copy of whatever you see on your monitor.Speaker/Headphone: A device that allows you to hear sounds. Speakers may either be external or built into the computer.
Central Processing Unit (CPU) and Memory
The Central Processing Unit (CPU) is a device that interprets and runs the commands that you give to a computer. It is the control unit of a computer. The CPU is also referred to as the processor. Memory is where information is stored and retrieved by the CPU. There are three main types of memory. Random access memory (RAM): It is the main memory and allows you to temporarily store commands and data. The CPU reads data and commands from RAM to perform specific tasks. RAM is volatile, which means it is available only while the computer is turned on. The contents of RAM must be copied to a storage device if you want to save the data in the RAM.Read only memory (ROM): It is the memory that retains its contents even after the computer is turned off. ROM is nonvolatile, or permanent, memory that is commonly used to store commands, such as the commands that
check whether everything is working properly. Flash memory: It is a nonvolatile memory that retains data even after a computer is turned off. Unlike in ROM, you can erase or modify stored information.
Motherboard
The motherboard is the main circuit board inside a computer. It has tiny electronic circuits and other components on it. The motherboard connects input, output, and processing devices together and tells the CPU how to run. Other components on the motherboard are the video card, the sound card, and the circuits that allow a computer to communicate with devices like a printer. The motherboard is sometimes called a system board.
Expansion Cards
An expansion card is a circuit board that can be attached to a motherboard to add features such as video display and audio capability to your computer. An expansion card improves the performance of your computer and enhances its features. Expansion cards are also called expansion boards. Some types of expansion cards are described in the following list. Video card: It is connected to a computer monitor and is used to display information on the monitor.Network interface card (NIC): It allows a computer to be connected to other computers so that information can be exchanged between them.Sound card: It converts audio signals from a microphone, audio tape, or some other source to digital signals, which can be stored as a computer audio file. Sound cards also convert computer audio files to electrical signals, which you can play through a speaker or a headphone. You connect microphone and speakers to a sound card.
Storage Devices
You use storage devices to store computer information. Storage devices come in many forms. Some examples are hard drive or disk, CD-ROM, floppy disk, and DVD-ROM. Storage devices can be divided into two types, internal storage devices and external storage devices. Some common storage devices are as follows: Hard disk: A magnetic disk that is usually the main storage device on most computers. It can be an external or an internal device.
Floppy disk: A portable storage device that allows you to store a small amount of data. A disadvantage of this disk is that it can be easily damaged by heat, dust, or magnetic fields.CD-ROM: A portable storage medium that allows you to store 400 times more data than on a floppy disk. It is less prone to damage than a floppy disk.DVD-ROM: A portable storage medium that is similar to a CD-ROM; however, it can store larger amounts of data than a floppy disk or a CD-ROM. A DVD-ROM is commonly used to store movies and videos.
Ports and Connections
A port is a channel through which data is transferred between input/output devices and the processor. There are several types of ports that you can use to connect a computer to external devices and networks. Some types of ports are described in the following list. Universal serial bus (USB) port: You use this to connect peripheral devices such as a mouse, a modem, a keyboard, or a printer to a computer.FireWire: You use this to connect devices such as a digital camera. It is faster than a USB.Network port: You use this to connect a computer to other computers to exchange information between the computers.Parallel port and serial port: You use these ports to connect printers and other devices to a personal computer. However, the USB port is now preferred to connect peripheral devices because it is faster and easier to use.Display adapter: You connect a monitor to a display adapter on your computer. The display adapter generates the video signal received from a computer, and sends it to a monitor through a cable. The display adapter may be on the motherboard, or on an expansion card.Power: A motherboard and other components inside a computer use direct current (DC). A power supply takes alternating current (AC) from a wall outlet and converts it into DC power
