IT_Chapter_3A

The Keyboard

• The most common input device

– Must be proficient with keyboard

– Skill is called keyboarding

• How keyboard works

– Keyboard controller detects a key press

– Controller sends a code to the CPU

• Code represents the key pressed

– Controller notifies the operating system

– Operating system responds

– Controller repeats the letter if held

• All modern computers have a variant

• Allows users to select objects

– Pointer moved by the mouse

• Mechanical mouse

– Rubber ball determines direction and speed

– The ball often requires cleaning

The Mouse

• Optical mouse

– Light shown onto mouse pad

– Reflection determines speed and direction

– Requires little maintenance

• Interacting with a mouse

– Actions involve pointing to an object

– Clicking selects the object

– Clicking and holding drags the object

– Releasing an object is a drop

– Right clicking activates the shortcut menu

– Modern mice include a scroll wheel

• Benefits

– Pointer positioning is fast

– Menu interaction is easy

– Users can draw electronically

• Mouse button configuration

– Configured for a right-handed user

• Can be reconfigured

– Between 1 and 6 buttons

– Extra buttons are configurable

Variants of the Mouse

• Trackballs

– Upside down mouse

– Hand rests on the ball

– User moves the ball

– Uses little desk space

• Track pads

– Stationary pointing device

– Small plastic rectangle

– Finger moves across the pad

– Pointer moves with the pointer

– Popular on laptops

• Track point

– Little joystick on the keyboard

– Move pointer by moving the joystick

Ergonomics and Input Devices

• Ergonomics

– Study of human and tool interaction

– Concerned with physical interaction

– Attempts to improve safety and comfort

• Repetitive Strain Injury (RSI)

– Caused by continuous misuse of the body

– Many professions suffer from RSI

• Carpal Tunnel Syndrome

– Carpal tunnel is a passage in the wrist

– Holds nerves and tendons

– Prolonged keyboarding swells tendons

• Techniques to avoid RSI

– Sit up straight

– Have a padded wrist support

– Keep your arms straight

– Keyboard properly

– Take frequent breaks