Components of Computer

Input

• Any thing given to the computer is known as input such as instructions or data

• Converts raw data into electronic form

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Input Devices: Giving Commands

• Input devices are types of hardware that enable you to get programs, data, commands, and responses into the computer’s memory

Keyboard

Mouse

Stylus

Keyboard

• Traditional– Looks like typewriter with

extra keys

• Non-traditional

It is used for specific purpose– Fast food restaurants– Each key represents a food

item rather than a character

Keyboard

Main Keyboard

• Typewriter keys

• Special command keys

Keyboard

• Numeric Keys– Num Lock – toggle – On – numeric data & math

symbols– Off – cursor movement

• Cursor Movement Keys

Function Keys F1-F12

• Give commands

• Software specific

• F1 is the help key in most programs.

KeyboardSpecial Keys

Enter

Esc

Alt

Ctrl

Caps Lock

Shortcut

Windows

Shift

Shift:Output a capital letter or symbol when pressed along with an alphanumeric key.Select text for editing when pressed along with cursor movement keys.

Ctrl:Produces different results depending on the program you are using.Ctrl key combinations provide shortcuts for menu commands.

Alt:Produces different set of resultsIn windows, Alt key combinations enable you to navigate menus and dialog boxes without using mouse.

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Enhanced / Extended Keyboard

Types of Keyboard

• Enhanced or Extended keyboard – Typically 101 keys laid out in the QWERTY fashion; connected to the computer by a serial cable

• Cordless keyboard – Uses infrared or radio wave signals

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Ergonomic Keyboard

Types of Keyboard

• Ergonomic keyboard

– Designed to help prevent damage to nerve tissues in the wrist and hand due to repeated motion.

– It enables the user’s hands to remain positioned correctly while reducing bending and strain

– Designed for people who type for extended period and suffer from wrist and hand fatigue.

Pointing Devices

• A mouse is a small, lightweight input device.

• It is also called pointing device

• Position a pointer / cursor on the screen

• Controls drawing instruments in graphics applications

Pointing Devices Mouse

• Types– Mechanical– Optical– Wireless

• Features– Palm-sized– 1 or 2 buttons– Wheel

Mechanical

1. Contain a small rubber ball.

2. Ball rolls inside the case when you move the mouse on a flat surface.

3. Rollers and sensors send signals to the computer, telling distance, direction and speed of ball.

Optical

1. Emits a beam of light from its underside.

2. Uses the light’s reflection to judge the distance, direction and speed of its travel.

Wireless

1. Give computer users cordless accessibility to their mice and to interact with their computer.

PS/2 Port

The color-coded PS/2 connection ports:

Purple for keyboard

Green for mouse

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Other Types of Pointing Devices

Joystick

Touch Pad

Touch Screen

Trackball

Pointing Stick

Pen

Other Pointing Devices

• Trackball– Upside-down mouse– Ball on top– Roll ball with hand– Requires less space than

mouse– Laptop computers

• Touchpad– Pressure-sensitive pad– Cursor moves as you slide

your finger– Laptop computers

Other Pointing Devices

Joystick

• Short lever• Handgrip• Distance and speed of movement control pointer

position

Touch Screens

• Human points to a selection on the screen

• Touch Screen is a video display screen that receives input from touch of finger.

• Types– Senses finger pressure– Light pen for pointing

Touch Screens

– Self-help stations– Easy to use

– Where found• Malls• Government offices• ATM• Fast food restaurants• Drug stores

Pen-based Computing

• Small hand-held devices

• Electronic pen (stylus)– Pointer– Handwritten input

• Personal Digital Assistants (PDA)

Optical Scanners

• Optical recognition

• Light beam scans input data

• Most common type of source input

• Document imaging – converts paper documents to electronic form

• Converts scanned picture into characters – OCR

• Exact computer-produced replica of original

Types of Scanners

• Flatbed– One sheet at a time– Scans bound documents

• Sheetfeed– Motorized rollers– Sheet moves across

scanning head– Small, convenient size

Types of Scanners

• Handheld– Least expensive– Least accurate– Portable– Wide document causes problems

• Read barcodes which are patterns of printed bars appear on product packaging.

• Barcodes identify product and provide information about product such a price.

• BCR emits a beam of light that is reflected by the bar code image.

• Light sensitive detector identifies barcode image by recognizing bars.

• BCR converts printed bars into a code the computer can understand.

• Reader then feeds the data into the computer.

Bar Code Readers

Voice Input

• Speech Recognition– Translating voice to text is a capability

known as speech recognition.

• Speech recognition devices– Input via a microphone– Voice converted to binary code

• Problems– Speaker-dependent– Voice training

Voice Input

• Discrete work systems– Understand isolated words– Pause between words– Difficult for dictation

• Continuous work systems– Normal speaking pattern– Easy to use– Faster and easier to dictate

Digital Cameras

• Photos stored in electronic form

• No film

• Point and shoot

• Edit

Webcam• A digital camera designed to

take digital photographs and transmit them over the internet.

• (WEB CAMera) A video camera that attaches to a computer typically via USB or that is built into a laptop or desktop screen. It is used mostly for videophoning over networks such as Skype as well as to continuously monitor an activity and deliver the video to a Web server for public or private viewing.