lecture # 37 operating systems
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Lecture # 37
Operating Systems
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
• UNIX
• 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
File Types
• Folders• PowerPoint Slides• Microsoft Word
• How does the computer know the file type?
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
File Extensions - just a record
• Many extensions can map to the same program
Deleted Files
• Deleted files are not really gone
• Recycle folder is just a special folder
• Can sometimes recover files
Warning: Reformat drives if they have
personal information before getting rid of
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
Files, User Interfaces, and the OS
• Files: programs (.exe); data (.jpg, .html, .doc, etc.)
• User Interface: used to run programs and manage files and folders through the OS.
• User Interface also manages and controls other devices (printers, disk drives, displays, networks)
Communicating with the OS
User
UserInterface
… but what does a User Interface look like?
OperatingSystem
Look at your screen
DOS (Command-line) User Interface
DOS (Command-line) User Interface
The Command Prompt
Viewing the contents of a Folder
• In DOS “Folders” = “Directories”
• So type “dir” followed by enter at the command prompt:
D:\CS100\CS100 Lectures >dir
Viewing the contents of a Folder
• In DOS “Folders” = “Directories”
Viewing the contents of a Folder
• In DOS “Folders” = “Directories”
Viewing the contents of a Folder
• In DOS “Folders” = “Directories”
• So type “dir” followed by enter at the command prompt:
D:\CS100\CS100 Lectures >dir
• The prompt is the path in the folder tree
Getting to DOS
1. Start menu
2. Programs
3. MS-DOS Prompt
File Management
• Change Folder/Directory
• Make Folder/Directory
• Copy Files
• Delete and Undelete Files
• Rename Files
Change Drive/Folder/Directory
• GUI (Windows or Mac)- double click on folders (up & down the tree)
• DOS: to change from C:\> to D:\CS100- type “d:”- Then type “cd cs100” (cd = change directory)- Type “cd \” to get back to the root (top of tree)
Make Folder/Directory
• GUI (Windows or Mac)- File > New > Folder
• DOS: to make a new folder “gronk”- type “mkdir gronk”- To remove/delete: type “rmdir gronk”
Copying Files
• GUI (Windows or Mac)- “drag & drop”
• DOS: to copy a file “foo.doc” to d:\cs100- type “copy foo.doc d:\cs100”- To rename as you copy
Type “copy foo.doc d:\cs100\newname”
Deleting Files
• GUI (Windows or Mac)- drag to recycle bin (Windows) or trash (Mac)- Empty to really delete
• DOS: to delete a file “notworthkeeping”- type “del notworthkeeping”
• To delete every file in the current folder or directory:
- type “del *.*”
Renaming Files
• GUI (Windows or Mac)- Click on the name of the file …. Pause ….- Then click on it again and edit it
• DOS: to rename file “bug” to “itruns”- type “ren bug itruns”
Running Programs
• GUI (Windows or Mac)- Double click on the program or file … or …
- “Drag & drop” file onto program
• DOS: to program “ItRuns”- type “ItRuns” and hit the enter key
Printing Files
• GUI (Windows or Mac)- Print from within the application … or …- “Drag & drop” file onto printer
• DOS: to print a text file “MyPaper”- type “print MyPaper”- type “type MyPaper” outputs it to the screen
Editing Files
• GUI (Windows or Mac)- Edit from within the application … or …- Open with Notepad as shown with html files
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