GIT 335 Lecture 51 Arizona State University Department of Technology Management GIT 335 Computer...

GIT 335 Lecture 5 1

Arizona State University

Department of Technology Management

GIT 335Computer Systems Technology

Lecture 5

Hardware – Input and Output

Dr. Thomas Schildgen, Professor

GIT 335 Lecture 5 2

Lecture 5

Introduction to Information Technology

Content taken from the McGraw Hill Textbook Chapter 5

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Hardware: Input & Output

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Input & Output

• Input Hardware– Devices that translate data into a form the

computer can process– Translates words, numbers, sounds, and

pictures into binary

• Output Hardware– Devices that translate information processed by

the computer into a form humans can understand

– Translates binary into words, numbers, sounds, and pictures

GIT 335 Lecture 5 5

Input Hardware

• Keyboards: convert letters, numbers, and characters into electrical signals

– English keyboards differ from foreign language keyboards

– Follow this link to see what a Russian Cyrillic keyboard layout looks like• http://www.geocities.com/fontboard/cyrillic.html

– Even languages that are close to ours like German have different keyboard layouts, such as can be seen on Microsoft’s web site• http://www.microsoft.com/globaldev/keyboards/kbdgr.htm

– Even touch typists must watch their fingers when they travel to Internet Cafes in foreign countries!

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Input Hardware

How keyboards work: You press a key This interrupts the current flowing through the circuits Processor determines where the break occurs It compares the location of the break with the (x,y) character

map for the language on the keyboard’s ROM chip A character is stored in 16-byte keyboard memory buffer Then sent to PC as a data stream via wire or wireless

connection OS interprets its own operating-system-specific commands

and sends the others to the application for interpretation

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Input Hardware

Keyboard types 104 – 108 keys desktop standard 80 – 85 keys for laptops

Wired Connect to CPU via a serial or USB port

Wireless use either IR (infrared) technology Radio Frequency (RF) technology Require line of sight to connect Virtual keyboard used with PDAs and smartphones

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Input Hardware Terminal Types

Dumb Terminals a.k.a. Video Display Terminal (VDT) Has display screen and keyboard Can do input and output only – no data processing

Intelligent Terminals Has screen, keyboard, and memory Can perform some local functions

Internet Terminals Powers directly up into a browser

Web terminal displays web pages on a TV set Network computer is a stripped-down PC to connect

people to networks Online game player connects to internet for online

gaming PC/TV merges a full-blown PC with a TV PDA is a handheld computer with a tiny keyboard

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Input Hardware

PDA Keyboards Problem: Make them too small and they are

unusable Problem: Make them too big and the PDA is too

big Solutions:

Some PDAs use a stylus Some PDAs use a foldable keyboard Some PDAs use a one-hand mini-keyboard

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Input Hardware Pointing Devices

Control the position of the cursor or pointer on the screen and allow the user to select options displayed on the screen

Mouse is the principal pointing tool Rolls around on a mouse pad or desktop and directs a pointer

on the computer’s display screen Ball inside the mouse touches the desktop and rolls around Two internal rollers touch the ball One roller picks up motion in x (up), the other in y (down) The rollers turn a shaft that spins a disk that breaks an LED

signal into light pulses that are seen by an infrared sensor Processor chip in mouse reads the pulses and turns it into

binary



Trackball A movable ball mounted on top of a stationary device Good for locations where a mouse couldn’t move enough Requires more frequent cleaning to remove finger oils

Pointing Stick Looks like a pencil eraser in the lower center of a laptop

keyboard Touchpad

To use: slide your finger over this small flat surface Click by tapping you finger on the surface May require more practice to use than a mouse



Touch Screens A video display screen sensitized to receive input

from a finger Cruder than a mouse, because fingers are big Problems: touch screens that show a display that

is not precisely aligned with the input

Pen input Use a pen-like stylus for input rather than typing

on a keyboard Use handwriting recognition to translate cursive

writing into data


Input Hardware

Light Pen A light-sensitive pen-like device that uses a wired

connection to a computer terminal Bring the pen to the desired point on the display screen

and press a button to identify the screen location Used in situations that require gloves Less crude than a touch screen

Digitizer Uses an electronic pen or puck to convert drawings and

photos to digital data Digitizing tablets are used in architecture


Input Hardware

Digital Pen Writing instrument Writers can write on paper A tiny camera in the pen tip captures the writing A microchip in the pen converts the pen to digital ink The writing is sent as an image file to the computer Original versions: Logitech’s IO pen and Leapfrog’s FLY

Fusion pen required special paper Later versions, like Mobile Digital Scribe do not require

special paper


Input HardwareScanning & Reading Devices

Source Data Entry devices create machine-readable data and feed it directly into the computer Scanners

Use light-sensing equipment to translate images of text, drawings, and photos into digital form

Image scanners are used in electronic imaging Resolution refers to the image sharpness, measured in

dots per inch (dpi) Flatbed scanners work like photocopiers – the image is

placed on the glass surface, then scanned Other types are sheet-fed, hand-held and drum


Input HardwareBar-Code Readers

Photoelectric (optical) scanners that translate bar code symbols into digital code

The digital code is then sent to a computer The computer looks up the item and displays its name

and pricing info Bar code types

1D holds up to 16 ASCII characters 2D can hold 1,000 to 2,000 ASCII characters 3D is “bumpy” code that differentiates by symbol

height Can be used on metal, hard rubber, other tough surfaces


Input HardwareMark Recognition Readers

Bar code readers MICR – Magnetic-ink character recognition

Uses special magnetized inks Must be read by a special scanner that reads this ink

OMR – Optical mark recognition Uses a special scanner that reads bubble marks Used in standardized tests like the SAT and GRE

OCR – Optical character recognition Converts scanned text from images (pictures of the

text) to an editable text format You use this to read in non-computer documents where

you don’t have the source files


Input HardwareFax Machines

Facsimile Transmission Machines – scan an image and send it as electronic signals over telephone lines to a receiving fax, which prints out the image on paper Dedicated fax machine

Is a stand-alone unit that only sends and receives faxed documents

Fax modem Is a circuit board installed in the PC Is a modem that can send and receive faxes

Can send documents directly from your word processor to a fax machine

Saves you printing out the document, then faxing it


Input HardwareAudio Input Devices

Records analog sound and translates it into digital files for storage and processing

Two ways to digitize audio Sound Board

An add-on board in a PC that converts analog sound to digital sound, stores it, and plays it back to speakers or amp

MIDI Board Stands for Musical Instrument Digital Exchange Uses a standard for the interchange between musical

instruments, synthesizers, and PCs


Input HardwareWebcams and Video-input Cards

Webcams Video cameras attached to a computer to record live

moving images then post them to a website in real time

Require special software, usually included with the camera

Frame-grabber video card Can capture and digitize 1 frame at a time

Full-motion video card Can convert analog to digital signals at rates up to

30 frames per second Looks like a motion picture


Input HardwareDigital Cameras

Use a light-sensitive processor chip to capture photographic images in digital form and store them on a small diskette in the camera or on flash memory cards Most can be connected to a PC by USB or

FireWire Can allow you to take more pictures and decide

which ones to print and save But pictures are subject to loss by diskette or

flash memory failure or computer virus if you store them on the PC


Input HardwareCamera Phones

Digital cameras are now on cellphones Convenience of being able to take photos, then

instantly email or message them to someone else Can provide instant record of traffic accidents, etc


Input HardwareSpeech-Recognition Systems

Uses a microphone or telephone as an input device. Converts a person’s speech into digital signals by comparing against 200,000 or so stored patterns. Used in places where people need their hands free –

warehouses, car radios, stock exchange trades Helpful for people with visual or physical disabilities that

prevent them from using other input devices Still not easy enough to use to substitute for the

mouse/keyboard for fast document processing ScanSoft and Nuance Fonix Speech Aculab Verbio


Input HardwareRFID Tags

Radio-frequency ID tags are based on an identifying tag with a microchip containing specific code numbers Scanners use radio waves to read them and match the

codes to a database Enables items to be tracked without physical contact

Drivers put RFID tags in cars to automatically pay tolls FDA is tagging certain drugs with RFID to avoid

counterfeits Carmakers are using it for car electronic keyless entry RFID tags are implanted under skin of pets to aid in

recovery and identification when they get lost


Input HardwareBiometrics

The science of measuring individual body characteristics, then using them to identify a person through a fingerprint, hand, eye, or facial characteristic Becoming a big business as more companies become

concerned about security Makes identity theft much more difficult when records are

identified by biometrics as well as passwords For more information see

http://www.xtec.com/ http://www.identix.com/ http://www.precisebiometrics.com/


Output Hardware

Softcopy Data that is shown on a display screen or is in

audio or voice form; exists electronically Output that is ephemeral in nature

Hardcopy Printed and film output Output that is more permanent in nature


Output HardwareDisplay Screens

Making a good choice when choosing a display Dot pitch (dp) is the amount of space between adjacent

pixels (picture elements) on screen The closer the pixels, the crisper the image Get .25 dp or better

Resolution refers to the image sharpness The more pixels the better the resolution Expressed in dots per inch (dpi)

Color depth or bit depth is the number of bits stored in a dot The higher the number the more true the colors 24-bit color depth is better than 8-bit color depth

Refresh rate is the number of times per second the pixels are recharged – a higher rate gives less flicker


Output HardwareMonitors

Cathode Ray Tube (CRT) is a vacuum tube used in a computer or terminal display screen Watch the PC ads to make sure your monitor is

included Flat panel displays are made of 2 plates of glass

separated by a layer of liquid crystals that line up to transmit or block light Preferable to CRTs because they take up less

room on the desktop Latency problems make them less desirable for

online games players


Output HardwareMonitors

Video Standard

XGA SXGA UXGA QXGA WXGA WUXGA

Principal resolution (pixels) 1024 x 768 1280 x 1024 1600 x 1200 2048 x 1536 1,386 x 768 1,920 x 1,200


Output HardwarePrinters

Impact Printers

Laser Printers

Inkjet Printers

Thermal Printers

Form characters or images by striking a print hammer or wheel against an ink ribbon Dot matrix printers

Use drums and toner like in photocopiers Page Description Language (PDL) PostScript and PCL are PDL types Produce crisp, professional pages

Spray ink from 4 nozzles at high speed Quiet, inexpensive color printers Often less precise than laser printers

Low to medium resolution printers that use thermal paper that darkens in time


Output HardwarePlotters

A specialized output device designed to produce large high-quality graphics in a variety of colors The earliest output device that could produce

graphics Pen plotters use one or more colored pens Electrostatic plotters lie partially flat on a table

and use toner like photocopiers Large-format plotters are large-scale inkjet

printers used by graphic artists


Output HardwareMixed Output

Sound output You need a sound card and sound software Good equipment can produce very high-quality 3-D sound

Voice Output TTS systems (text to speech) are becoming popular Requires a sound card and speakers with TTS software

Video Output Requires a powerful processor and a video card Video files are large, so a lot of storage is needed too.


I/O Quality of Life: Health & Ergonomics

PCs impact health Overuse injuries and repetitive stress injuries

Result when muscle groups are forced through fast, repetitive motions

May effect data-entry operators who average 15,000 keystrokes an hour

May effect PC users whose monitor, keyboard, and workstation are not arranged for comfort

Carpal tunnel syndrome is caused by pressure on the median nerve in the wrist, caused by short repetitive movement

Computer vision syndrome is eyestrain, headaches, and double vision caused by improper use of computer display screens


I/O Quality of Life: Health & Ergonomics

Ergonomics is the methodology of designing a workplace to make working conditions and equipment safer and more efficient Keyboards must be placed at the correct height depending

on each worker’s size Monitor refresh rates must be fast enough to avoid

eyestrain Monitor heights must be correct for comfortable viewing Sound-muffling should be used for loud printers to reduce

workplace noise Wrist rests may help avoid carpal tunnel syndrome


Future of Input and Output

This is a fruitful area for research, including Intelligent sensors More data input from remote locations More source data automation Input help for the disabled More sophisticated touch devices Better speech recognition Improved digital cameras Gesture recognition


Future of Input and Output

This is a fruitful area for research, including Pattern-recognition and biometric devices Brainwave devices Better and cheaper display screens Improved video on PCs 3-Dimensional output Miniaturization for improved data transfer

speeds to I/O devices

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