Interacting with your ComputerChapter 2

Learning Objectives• Identify five key groups on standard computer

keyboard• Name six special purpose keys.• Five essential techniques for using a mouse• Common variants of the mouse• Five steps you can take repetitive stress injuries

from computer use.

Input Devices• Keyboard • Mouse • Trackballs• Track pads• Pen• Touch screen• Barcode reader• Image Scanner• Microphone

Keyboard?• Keyboard is primary input device for entering text and

numbers.• Standard keyboard includes 100 keys each key send s a

different signal to CPU.• Input devices used to type data into some sort of computer

system whether it be a mobile device, a personal computer, or another electronic machine. A keyboard usually includes alphabetic, numerical, and common symbols used in everyday transcription.

• Tablets and other computers with touch interfaces often don't include physical keyboards. However, most do have USB receptacles which allow external keyboards to be attached.

• Laptops and notebooks have integrated keyboards but, like tablets, can have external keyboards attached via USB.

The Standard keyboard Layout• The various models differ in size , shape and feel except for

a few special-purpose keys, most keyboards are laid out almost identically.

• The most common keyboard layout is the IBM Enhanced Keyboard. It has about 100 keys arranged in five groups.

Parts of a Keyboard:• Alphanumeric Keys• Modifier Keys• Numeric Keypad• Function Keys• Cursor-movement Keys• Special-purpose Keys

Alphanumeric Keys:

The area of the keyboard that look like typewriter’s keys are arranged in the same way on almost every keyboard. Sometimes this common arrangement is called QWERTY.

Modifier Keys:

Key on the keyboard that is only used in conjunction with another key. For example, on an IBM compatible computer, the Alt, Ctrl, and Shift keys are modifier keys. On the Apple Macintosh computer, the Control, Option, and Shift keys are modifier keys. Modifier keys are often used in conjunction with other keys to perform computer keyboard shortcuts. For example, in many text editor programs pressing the Ctrl + A will select all text.

Numeric Keypad:

A separate set of keys on some keyboards that contain the numbers 0 through 9 and a decimal point arranged as on an adding machine. Numeric keypads make it easier to enter large amounts of numeric data. Frequently, the keys on the numeric keyboard also serve as cursor .

Function keys:

The function keys, which are labeled F l, f 2 ,and so on usually arranged in a row along the top of the keyboard. They allow you to input commands without typing long strings of characters or navigating menus or dialog boxes. Each function key's purpose depends on the program you are using. For example, in most programs, F l is the help key.

The 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:

In addition to the five groups of keys described earlier, all IBM*compatible keyboards feature six special-purpose keys, each of which performs a unique function.

Start. This key, which features the Windows logo (and is sometimes called the Windows logo key), opens the Windows Start menu on most computers. Pressing this key is the same as clicking the Start button on the Windows taskbar.

Shortcut: This key, which features an image o f a menu, opens an on-screen shortcut menu in Windows-based application programs.

• The page up and page down keys let you “flip“ through a document, screen by screen, like turning the pages of a book. Press page up to jump to the previous screen; press page down to jump to the next.

• The Escape key's function depends on your program or operating environment Typically, the Esc key is used to “back up" one level in a multilevel environment.

•The print screen key allow the user to capture whatever is shown on the screen as an image. This key does not work with all programs.

• In some programs, scroll lock causes the cursor to remain stationary on the screen, and the document's contents move around It. This key doesn't function at al in some programs.

•In some programs, the pause key can be used to stop a command In progress.

•Delete removes one character at a time at the cursor's location, cam erases characters to the right to the cursor.

•The Insert key Batches some programs from Insert mode" (in which text is inserted into the document at the cursor) to “overtype mode(in which new text is typed over existing text),and vice vena.

How a computer accepts input from the keyboard.

1. Key is pressed on the keyboard.

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

3. Keyboard buffer sends interrupt request to the system software.

4. System software responds to the interrupt by reading the scan code from the keyboard buffer.

5. System software passes the scan code to the CPU.

Mouse•The pointer (also called the mouse pointer) is an on-screen object, usually an arrow, that is used to select text; access menus; and interact with programs, files, or data that appear on the screen

• Mechanical mouse– Rubber ball moves– Rollers send information about speed and direction to system

software– The ball often requires cleaning

Rightclick The mouse is a fairly

intuitive input device.

When it gets sluggish, turn itover and remove the cover plate.

Carefully clean the ball and rollers.

Leftclick

• Optical mouseLight shown onto mouse padReflection 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

Variants of the MouseTrackballs

Upside down mouseUser moves the ballUses little desk space

Track padsStationary pointing deviceSmall plastic rectangleFinger moves across the padPointer moves with the pointerPopular on laptops

• Track point– Little joystick on the keyboard– Move pointer by moving the joystick