Keyboard and Mouse

A computer can have a variety of input devices. This allows the user to control the computer in different ways, or to input different types of data into the computer. The most common input device is the keyboard. Another very common input device is the mouse. This is used to control the computer when the operating system has a graphical user interface. There are different types of mouse but the one illustrated in this unit is very common.

The computer keyboard is an electronic device with keys arranged like earlier typewriter keyboards, but with extra keys. Because the output of the keys are controlled by the computer program, their function can vary. For example, the print screen key sometimes copies the screen to the memory and sometimes copies it to a printer depending on the program used. The arrangement of the keys varies but most desktops PCs have an external keyboard with keys divided into sections including the main keyboard, the function keys, the editing keys, and the numerical keypad.

The connection of computers throughout the world is known as the Internet. This allows users to send electronic mail messages (email) to each other. Each user has his or her own unique email address. The email address is made up of two main parts, the user identifier and the computer system identifier. For example:

Jim Smith @ ed.ac.uk

(user identifier) (computer system identifier)

The @ sign is used to separate these main identifiers. A dot is used to separate the parts of each identifier. Note that there is usually no dot at the end of an email address.

Linked document pages on the Internet form what is known as the World Wide Web (WWW or Web). Each webpage has its own unique address. Web addresses often, although not always begin with http://www. The two forward slashes are commonly read as double slash. A dot is used to separate each main part of an address, and slashes are used to separate sub-area of the address.

For example:

http://www.microsystems.com/newproducts/downloads