File Management & Windows Explorer

1. What 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! File Management & Windows Explorer

2. 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 filesare storagecontainers 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) Files and File Management File types

3. DOCUMENT files • created by an application program. • alphanumeric characters, numbers, pictures, sounds. • PROGRAM files (executable) • created by an programmer • called Executablefiles • 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

4. PROGRAM files (source) • created by an programmer • called Source files • usually stored as a readable text file (e.g. ASCII) • need translation before they can be executed by CPU • Examplesource 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-executedbatch file: “autoexec.bat”

5. First, two important digressions: Recall two-level storage: Primary memory: “memory” Secondary memory (auxiliary): “storage” Using files • Recall from Chapter 1-A (pp 11-13) that software also has two basic levels: • Applications software like Word, Excel, or Quake • Systems software the operating system

6. OK: so what happens in storage as we use computer files? • You turn the computer ON: • System boot-uphappens … • 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 memory

7. Processor Input Output COMPUTER SYSTEM Main Memory Non-Volatile bootstrap program Volatile Auxiliary Storage • - OS programs: • - Kernel (main supervisor) • - Application program loader • - Copy, Rename, Move, … routines • - APPS: Word Excel PPT Quake • - DATA files: Letter MyPic Budget Also provides inputs Also saves outputs 7

8. 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; Load • 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:electronic memory is 1,000 to 100,000 times faster than electromechanical storage. Proc. Main Memory Auxiliary Storage

9. 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? Demo: Different ways to start a file. Digression: What kind of file is MS Word? How do you know which apps are currently open?

10. 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)? • PROTECTON ? • SAVE the document toa floppy or to the hard-drive! • SAVE regularly! Proc. Main Memory Auxiliary Storage

11. OK, so you save the text document. • 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? Proc. • 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 name Main Memory Auxiliary Storage

12. 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 that document? • Why not quit the application? • What is the difference betweenclosing a document and closinga program? Proc. Main Memory Auxiliary Storage

13. You’re finished doing word processing for 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 Memory Auxiliary Storage

14. In these previous examples • Things keep moving around from one type of MEMORY to another. • Later, we’ll examine more closely WHY we have different types of memory, what they are, and what they are good for. Using Files interactive lab – see Lab-03 • What happens “in the box”: save, save As, move, copy, delete, etc.

15. Rules determined by the OS File naming conventions (Win) • Early PC days ….. Dreadful: “eight dot three” • Windows 95/98/2000/XP: • Up to 255 characters (including the extension). • Letters, numbers, most symbols except \ ? : “ < > | • Not case sensitive • Cannot use reserved words Com1 Com2 AuxLpt1 Prn Nul • Filename extensions • Tells Windows OS what the file format is. • Some examples: (see text for more) .exe .com --Executables that user can run .sys .drv .dll --Executables that user cannot run .doc .txt .xls --Text and spreadsheet file formats .jpeg .gif .tif --Graphics file formats .wav .mid .mp3 --Sound file formats UNHIDE Folder view

16. File naming conventions (Others) Again, rules determined by O.S. • Mac OS • Up to 31 characters • Letters, numbers, most symbols except : • Case sensitive • No reserved words • Unix • From up to 14 to 256 characters (depends on version) • Letters, numbers, most symbols except \ ? “ < > |* ! @ # $ % ^ & ( ) { } [ ] ; • no space allowed (sort of...); confuses the command line • Case sensitive • Reserved words depend on version

17. Traditional file organization Early Operating systems for PCs: Remember what application you used; launch it first; then open data file. Organizing files: tendency to keep docs filed w/apps. Is that particularly useful to USER? Why or why not? File organization • Document-centric file organization • Thanks to newer OSs: • Open data file-- automatically launches app that created it. • SO WHAT? Why is this more useful to the user? Play With Extensions “Documentcentricity”

18. LOGICAL file storage/organization OS keeps a directory for each disk: A list of files stored on that computer disk Where OS keeps track of each file (fname, date, time, size…) Logical view of data storage. Later we will look into how the OS maintainstheir physical location on the disk (clusters).

19. Logical organization--way to organize & visualizewhere folders and files are stored on a disk…. • the OS helps us to do this • incorporates a hierarchical organization…. • Metaphor: sideways tree…. (next slide)

20. Trunk - Root directory - Disk drive or partition. Each ID’d by letter. What’s typical? Branches - Subdirectories (aka: Folders): Can be directly under root directory (main branch). Can be “nested” inside other subdirectories. (branch off main branch). Leaves - Files File specifications (paths): D:\Homework\Comp 4\Lab 3 D:\Letters\Family\Mom.doc File spec for John.doc? Metaphor: Hierarchical file org. Study text reading carefully before doing Lab-03.

21. File Management Tool in Windows 9x/Me/2000/XP Some useful shortcuts: Microsoft website More in Lab 3 Windows Explorer Demo

22. Traditional: Hierarchical file org restrictive Why? Future Trends

23. New Approach: Database style organization Efficient search Not a rigid hierarchy Desktop Search Tools (c. 2005) Google Toolbar Yahoo Toolbar Microsoft – MSN Toolbar Picasa (Google) for photos/videos Future Trends

24. Coming Soon: Database style organization inside the operating system Apple: Tiger Spotlight (2005) Windows: Longhorn WinFS (2006?) Future Trends