MICE AND POINTING DEVICES


The PC mouse was developed as an ergonomic device that allows its user to select data, menus, and adjust the location of an insertion point (cursor). The invention of the GUI, such as Windows, spawned the demand for the mouse. Today, if you notice a computer without a mouse attached, it probably has a touch-screen video display for inputting data and selecting menus. Many types of mice are available today. The main types of mice you should be familiar with for the exam are as follows:

Mechanical: This is the most common type of mouse in use. A mechanical mouse contains a hard rubber ball, wheels, and sensors. When the mouse unit is moved, the rubber ball moves in the same direction, which makes the wheels supporting the ball spin. The mouse’s built-in sensors detect the movement of the wheels. The sensors send the detected signal to the computer. If your mouse pointer does not respond correctly as you move about the screen, you may need to inspect the rubber ball inside the mouse unit for foreign particles.

Optical: There are no moving parts inside the optical mouse. This type of mouse uses an optical system with a sensor to calculate the x and y coordinates of the screen’s cursor.

Optomechanical: This is a combination of the mechanical and optical mouse. A rubber ball is used in conjunction with a photo-interrupter disk. Light-emitting diodes are used to detect mouse movements.

Serial Mouse

Almost every computer has at least one serial (COM) port. A serial mouse’s female DB-9 connector attaches to the computer’s male DB-9 (9-pin) serial port. (See Chapter 21 for more information on connectors.) Before connecting a serial mouse to a serial port, you should check your BIOS configuration settings to verify that a COM port is available for the serial mouse to use. Remember, IRQs are assigned to COM ports. If the COM port you want to use has already been assigned to a modem, the serial mouse may not work.

A serial mouse can be connected to a PS/2 mouse port with a serial-to-mini-DIN adapter.

PS/2 Mouse

Today, it is standard for new PCs to come with PS/2 mouse and keyboard ports. The PS/2 mouse is a PnP device that uses IRQ 12 by default. This default IRQ assignment frees up a COM port that was previously needed to support a serial mouse.

It is important that you do not unplug a PS/2 mouse when the system is turned on. Unplugging an ‘active’ mouse can cause serious damage to your system and your mouse.

USB Mouse

A Universal Serial Bus (USB) mouse is a hot-swappable PnP device. This means it can be plugged into an already powered-up system and will automatically be detected by the operating system. With most new operating systems, the USB mouse drivers (software used to support the mouse) are automatically installed.

Trackballs

A trackball is a mouse with a plastic ball housed on its topside that uses less desk space than a traditional mouse. A thumb or finger is used to maneuver the ball. Trackballs use optomechanical technology and are connected to a system with a PS/2 or USB connection.

Infrared Wireless Mouse

The wireless mouse uses Infrared (IR) technology. A beam of infrared light goes from a receiver, which gets its power from a serial or PS/2 port, to the mouse. There must be a clear path from the mouse to the receiver in order for the mouse to work properly. This is called line-of-site infrared technology.

Touchpads

A touchpad is a small pad that is sensitive to the touch. It is used as a pointing device with most laptop computers. You direct the mouse pointer on your computer screen by sliding your finger across a square or rectangular pad. Programs can be started and objects selected by tapping on the pad. A touchpad does everything a mouse can do and eliminates the need for a mouse tail (wire).

Joysticks

Joysticks are used mostly for computer games and Computer-Aided Design (CAD) programs. A joystick is a pointing device that is attached to a sound or video card’s Musical Instrument Digital Interface (MIDI) port, also known as a game port. The exam might ask you to identify the MIDI (game) port on a sound card. Do not confuse this port with a 15-pin video connection (see Chapter 21 for information on connectors). Like a mouse, a joystick can move the screen pointer in all directions.

Stylus

A stylus is a handheld pen-shaped device that is commonly used as a pointing or writing instrument to input text and interact with a computer. A stylus, which uses an electronic tip or head instead of ink, is used to input text or small pictures into computer devices such as PDAs (Personal Data Assistants) or touch screens. PDAs and touch screens typically use a digitized electronic tablet to accept responses from a stylus.




The A+ Certification & PC Repair Handbook
The A+ Certification & PC Repair Handbook (Charles River Media Networking/Security)
ISBN: 1584503726
EAN: 2147483647
Year: 2003
Pages: 390

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