Parts of Computer

A computer has various parts, and each part performs a specific function. This pare are being categories into Input devices and Output devices

You use input devices to provide information to a computer, such as typing a letter or giving instructions to a computer to perform a task. Some examples of input devices are described in the following list

· Mouse: A device that you use to interact with items displayed on the computer screen. 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.

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· Keyboard: A set of keys that resembles a typewriter keyboard. You use the keyboard to type text, such as letters or numbers into the computer.
The keyboard is an input device you use for typing commands or text into a computer.

The different types of keys on a standard keyboard are listed below:
· Alphanumeric Keys: These keys are used for entering letters and numbers.

· Special Keys: Keys such as Control (CTRL), SHIFT, SPACEBAR, ALT, CAPS LOCK, and TAB are special keys. These special keys perform special functions depending on when and where they are used.

· Punctuation Keys: Punctuation keys include keys for punctuation marks, such as colon (:), semicolon (;), question mark (?), single quotation marks (‘ ’), and double quotation marks (“ ”).

· Command Keys: Keys such as INSERT (INS), DELETE (DEL), and BACKSPACE are command keys. You use these keys to insert and delete text and objects. You can turn the
INSERT key either ON or OFF. When turned ON, the INSERT key helps you overwrite characters to the right of the insertion point. When turned OFF, the INSERT key helps you enter text or characters to the right of the insertion point, without overwriting this text or characters.

An insertion point is the blinking vertical line that indicates the location at which the inserted text appears. The DELETE key is used to remove typed text, characters, and other objects on the right side of the insertion point. The BACKSPACE key is used to remove typed text, characters, and other objects on the left side of the insertion point.

· ENTER or RETURN Key: The label on this key can be either ENTER or RETURN, depending on the brand of computer that you are using. You use the ENTER or the RETURN key to move the insertion point to the beginning of a new line. In some programs, it is used to send commands and to confirm a task on a computer.

· Navigation Keys: Keys such as the arrow keys, HOME, END, PAGE UP, and PAGE DOWN, are navigation keys. You use the arrow keys to move the insertion point up, down, right, and left. The HOME key is used to move the cursor to the left end of a line of text or the top of a document.

The END key, in contrast, moves the cursor to the end of a line or a file, depending on the program. The PAGE UP key is used to move one page up and the PAGE DOWN key is used to move one page down while viewing a document. The functions of PAGE UP and PAGE DOWN keys differ from program to program.

· Function Keys: Keys labeled from F1 to F12 are function keys. You use them to perform specific functions. Their functions differ from program to program. The function of the F1 key in most programs is to access the help file associated with a program. Some keyboards may have fewer function keys.

· Numeric Keypad: Not all keyboards have a numeric keyboard. If available, this is a separate set of keys with numbers from 0 to 9, the decimal point, special characters, and navigation symbols. The NUM LOCK key on this keypad allows you to switch between the numeric and the navigation keys.

· Windows Key: The key between the CTRL key and the ALT key is the Windows key. It has the Microsoft Logo or the Windows flag. This key is used to open the Start menu, or is used in combination with a second key to perform common Windows tasks. The exact use of the Windows key may vary from program to program.

· Microphone: A device that you can use to talk to people in different parts of the world. You can record sound into the computer by using a microphone. You can also use a microphone to 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 the page and translates it into a digital format, which 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 the live pictures to the other user. For example, a webcam allows your friends and family to see you when communicating with them.

You use output devices to get feedback from a computer after it performs a task. Some examples of output devices are described in the following list.

· Monitor: A device that is similar to a television. It is used to display information, such as text and graphics, on the computer.

· 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: Devices that allow you to hear sounds. Speakers may either be external or built into the computer.

The central processing unit (CPU) is a device that interprets and runs the commands that you give to the computer. It is the control unit of a computer. The CPU is also referred to as the processor.

MEMORY
Memory is where information is stored and retrieved by the CPU.
There are two 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

THE MOTHERBOARD
The motherboard is the main circuit board inside the computer. It has tiny electronic circuits and other components on it. A motherboard connects input, output, and processing devices together and tells the CPU how to run. Other components on the motherboard include the video card, the sound card, and the circuits that allow the computer to communicate with devices like the printer. The motherboard is sometimes called a system board.

EXPANSION CARDS
An expansion card is a circuit board that can be attached to the motherboard to add features such as video display and audio capability to your computer.
An expansion card either improves the performance of your computer or 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 the computer monitor and is used to display information on the monitor.

· Network Interface Card (NIC): It allows the 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. The microphone and the speakers or the headphones connect to the 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 described in the following list.
· 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 the 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 the 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 is now the preferred method for connecting peripheral devices because it is faster and easier to use.

· Display Adapter: You connect a monitor to the display adapter on your computer. The display adapter generates the video signal received from the computer, and sends it to a monitor through a cable. The display adapter may be on the motherboard, or on an expansion card.

Power: The motherboard and other components inside a computer use direct current (DC). A power supply takes the alternating current (AC) from the wall outlet and converts it into DC power