Computers and Society IST 2710 Section 006 Class #3: 1/23/08

1/23/08Computers and Society, Winter 082 Topics Quiz 1 next week, first hour in class oQuiz 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

1/23/08Computers and Society, Winter 083 Starting Off #1 Initial the attendance sheet Pick up copies of oLab and Assignment

1/23/08Computers and Society, Winter 084 Quiz 1 Quiz 1 is next week, on January 30, first hour Topics handed out last week oAdd 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 else oIf you are behind and leave, you will get 50% attendance credit for that class 1/23/08Computers and Society, Winter 085

Eighth Mouse Action Word 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 1/23/08Computers and Society, Winter 086

Data Vs Information Data – Raw facts. What does it mean? oExample: 68 Information – Data with a label oExample – what the 68 means Bottom line – for a computer, it’s all data

Storing Information on a Disk #1 Disk is invisibly divided into Sectors (pie slices) and Tracks (onion slices). These intersect in 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

Storing Information on a Disk #2 oErasing a file – erase it in FAT only Read/write head – moves when changing tracks, very slow, minimize this oStore one file in contiguous tracks – in order oBut as files erased and rewritten, spread out o“Defragmenting” lines them up by track - speeds up computer Hard drive has several disks, stacked o“Cylinders” – do not have to move head oMore efficient allocation than FAT – NTFS, HPFS

Storing Information on a Disk #3 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 inside oNot magnetic but optical oLaser reads spots or pits on disk Capacities expanded last few years oDVD-ROM now Blu-Ray Vs HD-DVD (2 layers)

ASCII Code How does a computer store text? oAnswer: ASCII Codes, one byte per character oCode is on back of Assignment / Lab handout oTranslate to ASCII (ignore quotes): “Why is it so cold?” oTranslate to text: oCodes 128 to 255 for EҮuropean languages oUnicode, 2 bytes per character, international 1/23/08Computers and Society, Winter 0811

Converting Binary ↔ Decimal #1 Calculator does it! oStart > Programs > Accessories > Calculator oMake sure that View is Scientific, not Normal dec = decimal, bin = binary oPut Calculator in “from” mode, type number, click “to” mode Examples: oConvert 1101 binary to decimal oConvert 57 decimal to binary 1/23/08Computers and Society, Winter 0812

Converting Binary ↔ Decimal #2 Do binary addition 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 1/23/08Computers and Society, Winter 0813

Managing Your Files File path – how to find your file oFile path example: c:\My Documents\Computers\Lab1.docx oWhat 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. 1/23/08Computers and Society, Winter 0814

Tools for Seeing Your Files My Computer – desktop icon or Start oClick Folders button, click on a folder to see its contents oFolder can hold folders and files oFolders do not have information, only files do Windows Explorer – Start > Programs > Accessories > Windows Explorer “Keep your file safe tonight Walk the path from left to right” 1/23/08Computers and Society, Winter 0815

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 oTyping replaces selection 1/23/08Computers and Society, Winter 0816

Making Folders #2 Double-click on icon for First Use File > New > Folder to make a folder inside First – Call it Second oHow 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 1/23/08Computers and Society, Winter 0817

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 1/23/08Computers and Society, Winter 0818

Review for Quiz Go over Topics sheet Ask questions on the ones you aren’t sure of Imagine each one as a Quiz question 1/23/08Computers and Society, Winter 0819

Now, Lab 2