Operating Systems

• Programs for performing surgery

• NOT!

–Sorry I got carried away

Operating Systems

• Program that starts when you turn on your computer

• Controls devices (printers, disk drives, displays, networks)

• manages information in files and folders

• runs other programs

Example Operating Systems

• Microsoft Windows– Windows 98– Windows 2000– Windows XP

• UNIX– Linux (Open Source)– HPUX (Hewlett-Packard)– AIX (IBM)– Solaris (Sun)

• MacOS (Apple)

How are they the same?

• They have files

• They have folders or directories

• They run programs

How are they different?

• The user interface

• The things that a user must do to work with files, folders and programs

Managing Information

• Find files

• Look at the contents of files

• Organize your files and folders

• Create and delete files and folders

• Printers and disks

What is a File?

• An array of bytes

• What do those bytes mean?– Depends on the type of file

• Word, Excel, Gif, HTML, Jpg, VRML, Java

Finding files

• By Address - – every file has a particular address on a

particular disk drive– We don’t want to know

• By Name– Pathname in a tree of folders (directories) and

files

• By Search

Files, Folders and Names

Root of the tree

Files, Folders and Names

Disk where my files are stored

Files, Folders and Names

Files, Folders and Names

Files, Folders and Names

Files, Folders and Names

Path name

Files, Folders and Names

Up the tree

Files, Folders and Names

Up the tree

Files, Folders and Names

Up the tree

Files, Folders and Names

Files by Search

Do a searchFolder to search in

Partial name to search for

Files by Search

Files and Folders FoundPathnames of where they are in the tree

Other Searches

Content text rather than name

Other Searches

• By the date last modified

Censored

Viewing a File

• To look at a file we must run another program

• Run the program on double-click

• Which program will the OS run?– Depends upon the type of the file– How do we know the type of the file?

File Types

• Folders• PowerPoint Slides• Microsoft Word

• How does the computer know the file type?

Showing File Extensions

Showing File Extensions

Showing File Extensions

• An extension is at the end of the file name

• Each extension has a program associated with it– .ppt => PowerPoint– .doc => Word

Showing File Extensions

• Each extension has a program associated with it– .html => Netscape– .gif => Photoshop– .txt => Notepad

How do extensions get attached to programs?

• When the program is installed on your computer

File Extensions - just a record

• Many extensions can map to the same program

doc Microsoft Wordxls Microsoft Excelppt Microsoft PowerPoint

html Netscapejava Textpadtxt Notepadgif Photoshop

jpg Photoshoprtf Microsoft Word

max 3DS maxavi Media Player

mpg Media Playerwav Media Player

Organizing Files

• Create a Folder

Organizing Files

• Naming a file or Folder– Click -> click on the name -> type new name

Organizing Files

• Deleting a file or folder

• Drag to Recycle

Deleted files are not really gone

Recycle Bin is just a special folder

Other DevicesCD-ROM, ZIP, Network

What is a Program?

• A special file with extension .EXE

OS Running a program

• Reads the bytes from the file

• Places the bytes into memory

• Tells the computer to start running the instructions in those bytes

Operating Systems Review

• Everything is just a big tree– Files– Folders

• OS has record with a program name stored under each extension name

• A program is just a file filled with instructions for the computer