CHAPTER NUMBER: 2(A)

Interacting With Your Computer

OVER VIEWTHE KEYBOARD:ITS AN INPUT DEVICE FORENTERING NUMBERS &TEXTS.

THE MOUSE:ITS AN INPUT DEVICETHAT YOU CAN MOVE AROUNDAND CONTROLS POINTER.

THE KEYBOARD ITS AN INPUT DEVICE FOR ENTERING TEXT

AND NUMBERS. KEYBOARD HAS ABOUT 100 KEYS.

THE ALPHANUMERIC KEYS

The alphanumeric keys _ the area of keyboard that looks like a typewriter’s keys.

This arrangement is called the QWERTY because the first SIX keys on top of the row of letters are Q,W,E,R,T,Y.

THE MODIFIER KEYSMODIFIER KEYS

SHIFT

ALT

CTRL

The SHIFT,ALT and CTRL keys are called MODIFIER KEYS because they modify the input of other keys.

THE NUMERIC KEYS

The numeric keypad looks like a calculator’s keypad, with its 10 digits andmathematical operators(+, - , *, /).

Numeric keys also features NUM LOCK key.

THE FUNCTION KEYS

The function keys, which are labeled F1,F2 and so on are usually arranged in row along

the top of the keyboard.

CURSOR-MOVEMENT KEYS

Most standard keyboards also include a set of cursor-movement keys , which let you move

around the screen without using a mouse.

SPECIAL-PURPOSE KEYS

IBM-compatible keyboard features six special-purpose keys, each of which

performs a unique function.

How the Computer Accepts Input from the keyboard

KEYBOARD CONTROLLER

1. A key is pressed on the keyboard

KEYBOARD BUFFER

SYSTEM SOFTWARE

4.The system software respond to the interrupt by reading the scan code from the keyboard buffer

2.The keyboard controller sends the scan code for the key to the keyboard buffer.

3.The keyboard controller sends an interrupt request to the system software

5.The system software passes the scan code to the CPU.

The Mouse A mouse is an input device that you can move

around on flat surface(usually on a desk or keyboard tray) and controls the pointer.

PRIMARY BUTTON:

1.Click2.Double-Clicking3.Selection4.Dragging

SECONDARY BUTTON:

1.To bring menus

Variants of the Mouse

The primary goal of “mouse variants” are to

provide ease of use while taking up less space than a mouse.

Following are some variants of mouse explained in this chapter :

TRACKBALL TRACKPAD TRACKPOINT

TRACKBALLS

Trackball is a pointing device that works like an upside-down mouse you rest your index finger or thumb on an exposed ball, then place your other fingers.

You do not have to move the whole device , a trackball requires less space.

BALL:Move the ball to move the

pointer on the screen

TRACKPADS

The movement of a finger across a small touch-sensitive surface is translated into pointer movement on computer

screen. Touch sensitive screen maybe only 1.5 or 2 inches, so

finger never has to move far.

TRACKPOINT

Many portable computers now feature a small joystick positioned near the middle of the keyboard , typically between the G and H keys . The joystick is controlled with either forefinger, and it controls movement of pointer on screen.

Ergonomics and Input Devices

The term ergonomically correct means that a tool or workplace is designed to work properly with the human body , and thus reduces the risk of strain and injuries.

REPETITIVE STRESS INJURIES

This ailment is called repetitive stress injuries (RSIs) or repetitive strain injuries and result from continuously using the body in a way it was not

designed to work.

CARPAL TUNNEL SYNDROME:A wrist or hand injury caused by using a keyboard for long period of time.

Avoiding Keyboard-Related Injuries

If you use computer frequently, you can avoid RSIs by adopting a few good work habits, and by making sure that your hardware and workspace are set up in an ergonomically friendly way.

Following are some ways to avoid serious keyboard related injuries:

CHAIR:1. Make it first priority to use comfortable chair.

USE ERGONOMIC KEYBOARD:2. An ergonomic keyboard allows you to hold your hands in more normal position while typing.

USE A PADDED WRIST SUPPORT: If you type a lot , a wrist support can be helpful by allowing you to rest your hands comfortably when you are not actually typing.KEEP YOUR WRIST STRAIGHT: While typing your hands should be in a straight line with your forearms.SIT UP STRAIGHT: Sit up straight and avoid crossing your legs in front of you or under your chair for long period.TAKE FREQUENT BREAKS: Get up and move around for a few minutes each hour, and stretch occasionally throughout the day.