Information and Communication Technology Fundamentals Credits Hours: 2+1 Instructor: Ayesha Bint Saleem

Presentation Credits “Introduction to Computer” by Peter Norton “Using Information Technology” by Williams and Sawyer

How computers represent data and why?

5A-4 How Computers Represent Data Number systems A manner of counting Several different number systems exist Decimal number system Used by humans to count Contains ten distinct digits Origin: Probably because human beings normally have 10 fingers Digits combine to make larger numbers

5A-5 How Computers Represent Data Clocks have 24 hours Each hour  60 minutes Each minute  60 seconds When we time something, we count in seconds, minutes and hours

5A-6 How Computers Represent Data Computers use electronic switches called transistors A switch can either be ON or OFF Only two numeric values can be represented by one switch, 0 and 1 = 1= 0

Binary number system Used by computers to count Two distinct digits, 0 and 1 0 and 1 combine to make numbers How Computers Represent Data

5A-8 How Computers Represent Data Bits and bytes Binary numbers are made of bits Bit (Binary Digit) represents a switch A byte is 8 bits Byte represents one character

Any number from the decimal number system can also be written using binary number system Decimal to Binary conversion is required Each digit in the decimal number system has a place value Ones (10 0 ), Tens(10 1 ), Hundreds(10 2 ), Thousands(10 3 ) How Computers Represent Data

The place value is expressed in powers of to the power of digit position 10 is called the base of the Decimal number system In binary number system the base is 2 Place value is 2 to the power of digit position How Computers Represent Data Image Courtesy:

Conversion from decimal to binary Technique # 1 Map digits 0-9 to some binary values 0-9 are 10 digits 3 bits can have 8 combinations 4 bits can have 16 combination We would have to use 4 bits since 10 >  , 1 10  ,…, 9 10  This scheme is called Binary Coded Decimal (BCD)

Conversion from decimal to binary BCD So 9 10    What about binary numbers between and ? , , , , , Not Used! BCD is used only when you have to represent each digit of a number individually Digital Cricket Score Board

Conversion from decimal to binary Technique # 2 Lets count from 0 in both decimal and binary simultaneously and make sure every binary number is used 0 10                         And so on..

Conversion from decimal to binary Technique # 2 Did You notice some pattern? All odd numbers in decimal end with 1 in binary All even numbers is decimal end with 0 in binary The bits pattern repeats itself after the addition of every 1 on the Left Hand Side Same things happens in decimal E.g. digits 0-99 repeat after addition of digits 1-9 on the L.H.S

Conversion from decimal to binary Technique # 2 How would you represent in binary using technique number 2 ?? Some conversion procedure or formula is required so that we can convert any number from decimal to binary without having to count from 0 till that number

Conversion from decimal to binary Technique # 2 First Consider Conversion to binary to decimal Binary number system has a base ‘2’ For conversion calculate place value of each digit position and multiply by the corresponding digit value (0 or 1) (11001) =1x x x x x 2 0 = 1x x x x x 1 = = 25 10

Conversion from decimal to binary Technique # 2 Conversion from decimal to binary on board

Other Number Systems Hexa-Decimal Number System 16 possible values 0,1,2,…9,A,B,..F Base 16 Octal Number System 8 possible values 0,1,2,..7 Base 8

5A-19 How Computers Represent Data Text codes Converts letters into binary Standard codes necessary for data transfer ASCII – 7 bits + parity bit American English symbols Extended ASCII – 8 bits no parity Graphics and other symbols Unicode – 32 bits All languages on the planet

Output Devices

Sources for Output Seeing it Video card + Display Screen/Projector Hearing it Sound card + speaker Having it Printers

The Seeing part Monitor Most common output device Can display text, images, video/animation Video card Intermediary device between CPU and monitor Affects the quality of images displayed

4A-23 Monitors Most common output device Cathode Ray Tubes Flat Panel Display Categorized by color output Monochrome One color with black background Used for Text-only displays Grayscale Varying degrees of gray Used in low end portable systems to keep cost down Color Display 4 to 16 million colors

CRT Monitors Cathode Ray Tube (CRT) Most common type of monitor Phosphor is arranged in dots called pixels Phosphor are compounds which exhibit sustained glowing after exposure to energized particles such as electrons Electrons fired from the back using electron gun Electrons excite phosphor to glow Electron Gun aims at every pixel Line by line Starting from top left corner to right edge Then next line from left to right

CRT Monitors Cathode Ray Tube (CRT) Circuitry of the CRT adjusts the intensity of each beam Monochrome: pixel ON or OFF Grayscale: Intensity determines how brightly pixel glows Shadow mask is fitted with the screen Holes in mask ensures proper pixel is lit The electron gun systematically redraws every pixel on the screen, several times a minute Each pixel has a unique address used by computer to locate the pixel and control its appearance

CRT Monitors CRT color Phosphor dots arranged in triads Red, green, and blue dots Three colors blend to make colors Three Electron beams at each pixel Beams themselves are colorless Dots are colored Varying the intensity of each of the three beams creates new colors

CRT Monitors CRT drawbacks Very large Very heavy Use a lot of electricity

Flat Panel Monitors Liquid Crystal Display (LCD) Used in laptops, Desktop versions exist Solve the problems of CRT Made up of two glass plates separated by a special kind of liquid crystal Molecules of crystals line up in a way that alters their optical properties images are created on the screen by transmitting or blocking out light Active Matrix Display vs. Passive Matrix Display

Flat Panel Monitors Passive matrix LCD Pixels arranged in a grid Pixels are activated indirectly Row and column are activated by video card Color displayed by pixel is determined by electricity from transistors At the row end At the top of the column Limited viewing angle Animation can be blurry Pixels not refreshed very quickly Dual-Scan LCD Pixels scanned twice as often

Flat Panel Monitors Active matrix LCD Each pixel is activated directly by dedicated transistor Individual control over each picture Animation is crisp and clean Pixels refreshed much more rapidly Wider Viewing angle Thin Film Transistor Technology (TFT) – an enhancement Transistors arranged in a thin film Pixels have 4 transistors One each for red, green, blue One for opaqueness

Flat Panel Monitors Drawbacks to LCD More expensive than CRT Must sit directly in front of screen Can be more fragile than CRT

Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Pixel (picture element) the smallest unit on the screen that can be turned on and off or made different shades More on Monitors

Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors affecting screen clarity: Dot pitch (dp) the amount of space between the centers of adjacent pixels the closer the dots, the crisper the image Ranges between.15 mm and.40 mm Should be less than.22 More on Monitors Image Courtesy:

Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors affecting screen clarity: Resolution the image sharpness of a display screen; the more pixels there are per square inch, the finer the level of detail. Dot Pitch directly translates into resolution. How? Larger resolution numbers make smaller images. Why? More on Monitors

Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors affecting screen clarity: Color depth the amount of information, expressed in bits, that is stored in a dot The more bits in a dot or pixel, the more shades of gray and colors can be represented. More on Monitors

Copyright © Exclusive rights by The McGraw-Hill Companies, Inc. Factors affecting screen clarity: Refresh rate Phosphor dots fade quickly after electron gun charges them with electrons Need to be refreshed using electron beam the number of times per second that the pixels are recharged so that their glow remains bright is called refresh rate The higher the refresh rate, the more solid the image looks ( flickers less) RR of 100Hz means pixels are refreshed 100 times every second More on Monitors

Other Types of Monitors Paper-white displays High contrast between fore and background Used by Document designers Electro-luminescent displays (ELD) Similar to LCD Uses phosphor to produce light Plasma monitor Gas is excited to produce light

Video Cards Video card - Device between the CPU and monitor Removes burden of drawing from CPU Controlling electron gun etc At a resolution of 1024x768 and 24 bits/pixel, CPU must send 2,359,296 bytes to the monitor for each screen Screen changes constantly as user works

Video Cards Greater requirement for high-end video cards Video cards now have their own processor and RAM RAM is dual-ported Send screen-full data to monitor Receive screen-full of data from CPU Upto 512MB Chip rate determines refresh rate Also called video controller/ video adapter

Data Projectors Replaced overhead and slide projectors Project image onto wall or screen LCD projectors Most common type of projector Small LCD screen Very bright light Require a darkened room

Data Projectors Digital Light Projectors (DLP) A series of mirrors control the display May be used in a lighted room A projector is rated in lumens Measure of how bright the projector is Higher lumens ratings result in a brighter projector

Hearing It Sound System Sound Card Speakers/ Headphones Integral part of the computer experience Capable of recording and playback

Sound Systems Sound card Device between the CPU and speakers Converts digital sounds to analog Can be connected to several devices Modern cards support Dolby Surround Sound Speakers Convert electrical signals from sound card into sound waves

Sound Systems Headphones and headsets Replacement for speakers and microphones Offer privacy Does not annoy other people Outside noise is not a factor Headsets have speakers and a microphone

4B-45 Having it Printers! Impact printers Generate output by striking the paper Uses an inked ribbon Non-impact printers Use methods other than force Tend to be quiet and fast

4B-46 Commonly Used Printers Dot matrix printers Impact printer Used to print to multi-sheet pages Print head strikes inked ribbon Speed measured in characters per second cps Line printers Print entire line using large print head 3000 lines/minute Band printers Uses revolving band embossed with alphanumeric characters 2000 lines/minute

4B-47 Dot Matrix Print Head Resolution depends on number of pins on a print-head. More pins  greater resolution

4B-48 Commonly Used Printers Ink-jet printers Non-impact printer Inexpensive home printer Color output common using CMYK Cyan, magenta, yellow, black Sprays ink onto paper Speed measured in pages per minute Quality expressed as dots per inch

4B-49 Dots Per Inch

4B-50 Commonly Used Printers Laser printer Non-impact printer Produces high quality documents Color or black and white Print process Laser draws text on drum Toner, tiny ink particles, sticks to drum Toner melted to page using pressure and heat Color Printing Same process four times Different toner color each time CMYK

4B-51 Commonly Used Printers Speed measured in pages per minute 4 to 16 pages of text / minute Slower of graphics Quality expressed as dots per inch Commonly dpi both horizontally and vertically Upto 1200 dpi for professional quality printing

4B-52 Commonly Used Printers All-in-one peripherals Scanner, copier, printer and fax Popular in home offices Prices are very reasonable

4B-53 Comparing Printers Determine what you need Determine what you can spend Initial cost Cost of operating (ink toner + maintenance) Image quality (dpi) Speed (ppm)

4B-54 High-Quality Printers Special purpose printers Used by a print shop Output is professional grade Prints to a variety of surfaces

4B-55 High-Quality Printers Photo printers Produces film quality pictures Prints very slow Prints a variety of sizes

4B-56 High-Quality Printers Thermal wax printers Produces bold color output Color generated by melting wax Colors do not bleed Operation costs are low Output is slow Used for presentation graphics and handouts

4B-57 High-Quality Printers Dye sublimation printers Produces realistic output Very high quality Color is produced by evaporating ink Operation costs are high Output is very slow

4B-58 High-Quality Printers Plotters Large high quality blueprints Older models draw with pens Operational costs are low Output is very slow

3A-59 Ergonomics and Input Devices Ergonomics Study of human and tool interaction Concerned with physical interaction Attempts to improve safety and comfort

3A-60 Ergonomics and Input Devices 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

3A-61 Carpal Tunnel Syndrome

3A-62 Ergonomics and Input Devices Office hardware suggestions Office chairs should have Adjustable armrests and height Armrests Lower back support Desks should have Have a keyboard tray Keep hands at keyboard height Place the monitor at eye level

3A-63 Ergonomics and Input Devices Techniques to avoid RSI Sit up straight Have a padded wrist support Keep your arms straight Keyboard properly Take frequent breaks

Ergonomics and Monitors Eyestrain Fatigue of the eyes Steps to avoid Choose a good monitor Place the monitor 2 – 3 feet away Center of screen below eye level Avoid reflected light

Ergonomics and Monitors Electronic magnetic fields (EMF) Generated by all electronic devices EMF may be detrimental to health Although no conclusive study exists Steps to avoid Keep the computer at arms length Take frequent breaks Use an LCD monitor