1 Operating Systems Who’s in charge here?

2 What is an Operating System  Basically the boss of the computer  Facilitate communication  Maximize throughput  Minimize processing time  Optimize computer resources  Organize files  Provide security  Monitor system/alert user

3 Operating System (OS)  Allows the user (you) to interact with:  Applications (word, , Internet)  File management (open, save, delete)  Networking (connects to the Internet)  Hardware (CD drives, printers, scanners)  Memory (loading, sharing, saving)  Security (permissions, passwords)

4 Where does the OS Live?  Some computers store their operating system in ROM (such as cell phones and MP3 players)  Others include only part of it in ROM  The remainder of the operating system is loaded into memory (RAM) in a process called booting, which occurs when you turn on the computer

5 What does the OS Look Like?  The end user has a pleasant Graphical User Interface (GUI) which represents the OS

6 Who are the players?  Microsoft Windows (90% of market share)  DOS/Windows 3.1  Windows NT/95/98/ME/2000/XP/Vista  Apple – Mac OS X  Unix and variants  BSD, Sun Solaris, Unisys  Linux (FREE)  Palm OS / iPhone OS

7 Microsoft Windows  Originally, Microsoft Windows was a type of program, known as a shell, which put a graphical face on MS-DOS  With the introduction of Windows 95 in 1995, Microsoft began transitioning Windows from an operating system shell into a full operating system that seldom showed its MS-DOS roots  The latest Windows versions have no ties at all to the DOS past

8 UNIX and Linux  Multiple User Operating Systems  UNIX was developed at Bell Labs before personal computers were available  Linux was created by Linus Torvalds and continues to be a work-in-progress  Allow a timesharing computer to communicate with several other computers or terminals at once  Linux is free for anyone to use or improve  UNIX remains the dominant operating system for Internet servers

9 Common Features of an OS  Graphical User Interface (GUI) - Using mouse and graphics  Multitasking – Allow multiple programs to run at the same time  Multiprocessing – Allow different parts of the same program to run at once

10 What does that look like?

11 Preventing Chaos  The OS is responsible for preventing application conflicts and potential deadlocks WHAT???

12 Scenario  Dylan (the user) is running several different applications (multitasking) Microsoft Word iTunes – Music Player Firefox - Web browser MSN Messenger

13 But the processor can only do one thing at a time…

14 Chaos Solution

Chaos solution  The processor does a bit of work for MS Word (1), then a little bit of iTunes (2), a little bit of MSN (3), and a bit of Firefox (4) and goes back to the start.  The processor moves so fast that it looks like its running all 4 programs at once. 15

16 Summary  The Operating System is the BOSS  Applications (word, , Internet)  File management (open, save, delete)  Networking (connects to the Internet)  Hardware (CD drives, printers, scanners)  Security (permissions, passwords)

17 Sources  002/sept3.ppt 002/sept3.ppt  notes/Chapter-01.ppt notes/Chapter-01.ppt   11h6.pdf 11h6.pdf  OS.ppt OS.ppt   rces/comm4382/docs/OSTrends.ppt rces/comm4382/docs/OSTrends.ppt