computers and society ist 2710 section 006 class #3: 1/23/08

Computers and SocietyIST 2710

Section 006

Class #3: 1/23/08http://www.is.wayne.edu/drbowen/casw08

1/23/08 Computers and Society, Winter 08 2

Topics

• Quiz 1 next week, first hour in classo Quiz Topics sheet: Add the 6 types of computers

• If you fall behind in homework and/or labs• Eighth mouse action• Data Vs Information• ASCII Code• How is Data Stored on a Disk• Converting numbers with Calculator• File path, seeing your files• Question and Answer Review for Quiz 1• Lab period


Starting Off #1

• Initial the attendance sheet• Pick up copies of

o Lab and Assignment


Quiz 1

• Quiz 1 is next week, on January 30, first hour

• Topics handed out last weekoAdd the 6 types of computers

• Quiz will be copy and paste off of this sheet

• Review at the end of class

If You Fall Behind

• Starting next week, if you are two or more weeks behind on the homework or the labs, you must stay for the full class to get full attendance credit for that class.oBeing able to leave early is to work on the

labs somewhere elseo If you are behind and leave, you will get 50%

attendance credit for that class


Eighth Mouse ActionWord Only?

• In right or left screen margin, click and hold scroll button (and maybe click a second time)

• This shows a up/down arrow and a dot in the middle, and a “ghost” of this in margin

• Hold mouse above ghost, scroll up• Hold mouse below ghost, scroll down• Further from mouse scrolls faster


Data Vs Information

• Data – Raw facts. What does it mean?oExample: 68

• Information – Data with a labeloExample – what the 68 means

• Bottom line – for a computer, it’s all data

Storing Information on a Disk #1

• Disk is invisibly divided intoSectors (pie slices) and Tracks(onion slices). These intersectin areas also called sectors.oData is read/written into sectors.oEach sector in a file has the number of the

next sector• File Allocation Table (FAT) (old tech) lists

file names and which sectors for which files – about 1/3 of disk capacity


o Erasing a file – erase it in FAT only

• Read/write head – moves when changing tracks, very slow, minimize thiso Store one file in contiguous tracks – in ordero But as files erased and rewritten, spread outo “Defragmenting” lines them up by track - speeds up

computer

• Hard drive has several disks, stackedo “Cylinders” – do not have to move heado More efficient allocation than FAT – NTFS, HPFS


• Magnetic disks move same speed all the time, speed faster on outer tracks

• CD-ROM and DVD-ROM: single spiral track, constant speed, turns faster on insideoNot magnetic but opticalo Laser reads spots or pits on disk

• Capacities expanded last few yearsoDVD-ROM now Blu-Ray Vs HD-DVD (2 layers)

ASCII Code

• How does a computer store text?oAnswer: ASCII Codes, one byte per characteroCode is on back of Assignment / Lab handouto Translate to ASCII (ignore quotes):

“Why is it so cold?”o Translate to text: 66 101 99 97 117 115 101

32 105 116 96 115 32 77 105 99 104 105 103 97 110 33

oCodes 128 to 255 for EҮuropean languagesoUnicode, 2 bytes per character, international


Converting Binary ↔ Decimal #1

• Calculator does it!oStart > Programs > Accessories > CalculatoroMake sure that View is Scientific, not Normal

• dec = decimal, bin = binaryoPut Calculator in “from” mode, type number,

click “to” mode• Examples:

oConvert 1101 binary to decimaloConvert 57 decimal to binary


Converting Binary ↔ Decimal #2

• Do binary addition 111 + 10• Convert 111 and 10 and answer to

decimal, check value• Binary addition, also multiplication, give

same answer as decimal• Do binary multiplication 111 x 11• Convert 111 and 11 and answer to

decimal, check value


Managing Your Files

• File path – how to find your fileo File path example:

c:\My Documents\Computers\Lab1.docxoWhat do the parts mean? From broad to

particular• All the way on the left, drive• All the way on the right – dot separates extension

on right of dot from name on the left of the dot• Everything else is folders

folder, sub-folder, sub-sub-folder, etc.


Tools for Seeing Your Files

• My Computer – desktop icon or StartoClick Folders button, click on a folder to see

its contentso Folder can hold folders and fileso Folders do not have information, only files do

• Windows Explorer – Start > Programs > Accessories > Windows Explorer

• “Keep your file safe tonightWalk the path from left to right”


Making Folders #1

• Insert floppy diskette (how) – A: drive• Start either My Computer (showing

folders) or Windows Explorer• Click on A: icon (click on letters to change

the name)• Click File > New > Folder• Name is selected - type name – First

o Typing replaces selection


Making Folders #2

• Double-click on icon for First• Use File > New > Folder to make a folder

inside First – Call it SecondoHow would you make a second main folder

instead?• Open Word and save a file (content does

not matter) in the folder Second• Show all folders and the file in the program


Making Folders #3

• Take a screen shot, paste it into Word• This proves that you did it right• A homework problem• Will be on Quiz 1


Review for Quiz

• Go over Topics sheet• Ask questions on the ones you aren’t sure

of • Imagine each one as a Quiz question


Now, Lab 2