Summer Session II 2005, Page 1 Lec-03COMP 4—Power Tools for the Mind1Power ToolsWhat’s in the Box?File Management & Windows ExplorerWhat we’ll cover for this lecture topic:– Files and file management• File types•Using files• File naming conventions• File organization/hierarchy• Future Trends– Windows Explorer (tool)Excellent tutorials! Very important concepts! COMP 4—Power Tools for the Mind2Power ToolsWhat’s in the Box?Files and File Management• Soon you will learn how five different kinds of data can be represented in a computer.• How do we organize this data? It is all just a bunch of 0s and 1s, no?– Yes, but we logically organize these 0s and 1s into files.• Computer files are storage containers that hold all the 0s and 1s that represent all the data that belong to a single document or to a program.– DOCUMENT files– PROGRAM files (executable / source)• Kept track of by Operating System (OS)File typesCOMP 4—Power Tools for the Mind3Power ToolsWhat’s in the Box?• PROGRAM files (executable)– created by an programmer– calledExecutable files•stored as machine code•ready to be executed by CPU (“compiled” code)•examples:–application programs (Apps)–operating system programs (OS)–utilities (compression utility; backup utility; etc.)–some run at a user’s request; others at a program’s request• DOCUMENT files– created by an application program.– alphanumeric characters, numbers, pictures, sounds.COMP 4—Power Tools for the Mind4Power ToolsWhat’s in the Box?• PROGRAM files (source)– created by an programmer– calledSource files•usually stored as a readable text file (e.g. ASCII)•need translationbefore they can be executed by CPU•Example source files:– program source files• Turing (e.g. later you will write Turing programs)• Java / C / C++– script languages• JavaScript / VisualBasic Script– batch files• bunch of commands stored in a text file.• automatically-executed batch file: “autoexec.bat”COMP 4—Power Tools for the Mind5Power ToolsWhat’s in the Box?Using filesFirst, two important digressions:• Recall two-levelstorage:– Primary memory: “memory”– Secondary memory (auxiliary): “storage”• Recall from Chapter 1-A (pp 11-13) that software also has two basic levels:– Applications softwarelike Word, Excel, or Quake– Systems softwarethe operating systemCOMP 4—Power Tools for the Mind6Power ToolsWhat’s in the Box?• You turn the computer ON:– System boot-up happens …– Power reaches chips on the main circuit (mother board).– one chip is ROM memory that contains a bootstrap program– it instructs the processor how to copy (e.g. load) the operating system from the disk to the main memoryOK: so what happens in storage as we use computer files?Summer Session II 2005, Page 2 Lec-03COMP 4—Power Tools for the Mind7Power ToolsWhat’s in the Box?COMPUTER SYSTEMProcessorMain MemoryInputOutputAuxiliary Storage-OS programs:- Kernel (main supervisor)- Application program loader- Copy, Rename, Move, … routines- APPS: Word Excel PPT Quake- DATA files: Letter MyPic BudgetVolatileAlso providesinputsNon-Volatilebootstrap programAlso savesoutputs7COMP 4—Power Tools for the Mind8Power ToolsWhat’s in the Box?• What will happen INSIDE THE BOX whenWord is launched?– Hint: Where is the MS WORD program stored even before you switched the computer on? Where must it be stored (be copied to) so that we can use it? Why?– Remember: electronicmemory is 1,000 to 100,000 times faster than electromechanicalstorage. • Next, you want to create a new text document.– What’s in memory now?– Tell the computer to Start M.S. Word.• Other terms for Starting: Launch; LoadProc.Main MemoryAuxiliaryStorageCOMP 4—Power Tools for the Mind9Power ToolsWhat’s in the Box?• Exactly WHAT part of the computer system do you, the user, give this request to?– Hint: what part of the computer system knows how to handle that request?• In what ways can the user make that request?Digression:What kind of file is MS Word?How do you know which apps are currently open?Demo:Different ways to start a file.COMP 4—Power Tools for the Mind10Power ToolsWhat’s in the Box?– SO… MS Word provides a blank document window. You enter some text.• Where is that text being stored?• What happens if the machine freezes up (crashes)?Proc.Main MemoryAuxiliaryStorage–PROTECTON ?• SAVE the document toa floppy or to the hard-drive!• SAVE regularly!COMP 4—Power Tools for the Mind11Power ToolsWhat’s in the Box?– OK, so you save the text document.Proc.Main MemoryAuxiliaryStorage• Which two things happens “in the box” when you Save it?• What kind of file is it?• How many copies of that “file” are in existence at this moment, and where are they stored? • You make lots of changes to your document.– Where are those changes being stored?• OK, finished with your changes. Whatare your 3 options here?•Save– Replaces disk file with edited file.• Just Close. Don’t save.– Why would you want to do this?• Save As– Keep original: store newly edited fileunder a different nameCOMP 4—Power Tools for the Mind12Power ToolsWhat’s in the Box?– Now you want to open (in addition) a data file you saved yesterday.• First, where is it now? What happens “in the box” when you open it? Where is it then?– You’re finished with the first document ...• What is the minimum I should close to free main memory?• Exactly what happens “in the box” whenyou only close thatdocument?• Why not quit the application?• What is the difference betweenclosing a document and closinga program?Proc.Main MemoryAuxiliaryStorageSummer Session II 2005, Page 3 Lec-03COMP 4—Power Tools for the Mind13Power ToolsWhat’s in the Box?– You’re finished doing word processingfor this computer session.• What could you do now to free up memory? How?• Exactly what happens “in the box” when you do that?• How can you tell by looking at the desktop?– What happens if I delete (‘recycle’) a file:• from the hard drive?OS “moves” it to the recycle bin fromwhere can potentially be restoredlater.• from a floppy disk?Not moved to recycle bin. Cannoteasily be restored.Proc.Main MemoryAuxiliaryStorageCOMP 4—Power Tools for the Mind14Power ToolsWhat’s in the Box?– In these previous examples• Things keep