5. Input devices: a mouse (a mechanical mouse, an optomechanical mouse, an optical mouse, a cordless (wireless) mouse; main functions); touch panels; light pens; joysticks; microphones.

A mouse is a pointing hand-held device for use with a graphical user interface that lets you move a pointer (or cursor) and select items on the screen thus simplifying user's orientation on the display.

A scroll wheel lets you move through your documents or web pages. The pointer looks like an I-bar, an arrow or a pointing hand. The mechanical mouse is a simple, hard rubber ball mouse which has sensors that detect the movements of the mouse and translate them in moving the pointer on the screen.

The optomechanical mouse works on the same principle. The rollers have wheels on the end of them with evenly spaced holes. As the wheels spin, a light-sensitive optical device counts the number of holes that pass by and converts them to an "X" and "Y" axis.

An optical mouse has an optical laser sensor instead of a rubber ball and rollers underneath. The lasers detect the movement of the mouse and move the pointer accordingly. A cordless (wireless) mouse has no cable; it sends data via infrared signals or radio waves.

Mouse actions:

- to click, press and release the left button.

- to double-click, press and release the left button twice.

- to drag, hold down the button, move the pointer to a new place and then release the button.

- to right-click, press and release the right button; this action displays a list of commands.

In portable computers touch panels or touchpads are used instead of manipulators. Moving a finger along the surface of the touch pad is transformed into the cursor movement across the screen.

A light pen is a photosensitive penlike instrument with a light sensitive tip that is used to draw directly on a computer video screen or to select information on the screen by pressing a clip in the light pen or by pressing the light pen against the surface of the screen. The pen contains light sensors that identify which portion of the screen it is passed over. It can be used for drawing directly on the monitor screen or for reading printed optical characters or barcodes.

A joystick is a pointing device composed of a vertical lever that moves in multiple directions to navigate a cursor or other graphical object on a computer screen precisely and at high speed. It is particularly good for playing fast action games.

Microphone is a device used to input sound. You can also interact with your computer by voice with a voice-recognition system that converts voice into text, so you can dictate text directly onto your word processor

or email program.

6. Scanners (main functions, a flatbed (desktop) scanner, a film scanner, a hand held scanner, a barcode scanner, a pen scanner); digital cameras, camcorders, webcams: main functions and technical characteristics.

Input devices such as scanners and cameras allow you to capture and copy images into a computer.

A scanner is a peripheral that reads images and converts them into electronic codes which can be understood by a computer.

There are different types.

A flatbed (desktop) scanner is built like a photocopier and is for use on a desktop; it can capture text, colour images and even small 3D objects.

A film scanner is used to scan film negatives or 35 mm slides - pictures on photographic film, mounted in a frame. Hand held scanners are small manual devices that are passed manually across the surface of the image to be scanned. Scanning in this manner requires a steady hand, as an uneven scanning rate would produce distorted images.

Barcode scanners read barcodes on the products sold in shops and send the price to the computer in the cash register.

A pen scanner looks like a pen; you can scan text, figures, barcodes and handwritten numbers.

A digital camera doesn't use film. Photos are stored as digital data (bits made up of 1s and 0s), usually on a tiny storage device known as a flash memory card. You can connect the camera or memory card to a PC and then alter the images using a program like Adobe Photoshop, or you can view the images on a TV set. Many printers have a special socket so that you can print images directly from a memory card or camera.

A camcorder (camera+recorder), or digital video camera, records moving pictures and converts them into digital data that can be stored and edited by a computer with special video editing software. Digital video cameras are used by home users to create their own movies, or by professionals in computer art and video conferencing.

Webcams (short for Web cameras) let you send and receive live video pictures through the Internet. They're primarily used for video conferences - video calls - but they can be used to record photos and video onto your hard disk. The resolution of webcams is expressed in megapixels (million pixels). Webcams connect to the PC via a USB (universal serial bus) or FireWire port; they display video at 24 to 30 frames (pictures) per second. Some include a headset with a microphone and earpiece.