1. 1 ITSK 2611 Welcome

2. 2 Operating System

3. 3 What is an OS Resource Manager –Disk –Memory –CPU Device Manager –Printers –Video Card –Sound Card Utility Graphical User Interface (GUI)

4. 4 Managing Disk Computers have a hard drive. –This is where all long term information is stored –OS makes the drive look like a folder to us. In reality the drive is made up of many read heads, platters, cylinders, and sectors. A given file is usually stored in many small pieces all over the drive –The OS remembers where all the pieces are, and when we ask to see the file it quickly puts it all back together –This allows for better use of the available space. Different OS use different methods to store the files: –FAT, NTFS, E2FS.

5. 5 Managing CPU A CPU can only do one thing at a time. –So even when it looks like your computer is doing many things, its really doing them in a serial manner, just so quickly we can’t tell. Play MP3, Printing a document, Allowing you to type an email, downloading a web page. –The OS decides which process gets to use the CPU next, and for how long it can stay there.

6. 6 Managing Memory Each computer has a set amount of physical memory –32MB, 64, 128, 256, 512, 1024MB etc –Many applications today are huge. e.g. Outlook takes 12MB just to run, Netscape takes 10MB. –To a user it seems that you can load as many applications as you want. The OS decides how much memory each application gets When memory is not in use the OS will swap it to disk.

7. 7 Managing Devices Many Video, Sound, Network cards can perform pretty complex stuff these days. –Example, video cards which are optimized to compute 3D graphics. The OS needs to know how to use these special services, and when to use them. –A device driver explains to the OS what the device can do.

8. 8 GUI/Applications Today we are used to OS which provide us nice GUI’s and applications. –When a new version of Windows comes out the first thing we notice is how it looks. What games it came with What new application run on it. –We hardly notice how the OS it self actually works. Except when it crashes.

9. 9 UNIX/Linux

10. 10 Birth of UNIX Unix was created in 2 places at once. –AT&T Bell Labs (Lucent Technologies) –Berkley Standard Distribution Designed as a –Multi User –Multi Tasking OS. Sold commercially by AT&T and Berkley it was expensive.

11. 11 Along comes Linux In 1991 Linus Torvalds was a college student in Finland. –He was annoyed by Windows –Couldn’t afford UNIX for his PC –So he decided to write a very basic UNIX clone. –He released the kernel under the GPL (General Public License) Anyone can get the source code Any changes you make you must make public –Today Linux is as featured as any version of UNIX, and is freely available for almost any hardware platform.

12. 12 Linux Distributions Some software companies have grown up around Linux. –RedHat is the most famous. –They provide some value added services: Technical Support Documentation A repository for applications Some custom software –Install Script –Today the public is used to getting software which is easy to install and is already compiled.

13. 13 Why Linux? Strengths: –Very reliable Often Linux servers run for YEARS without reboots –OS is detached from applications Installing the latest version of IE won’t crash your system. –Free –Constantly being developed, and added to by 1000’s of coders all over the world Weaknesses: –Sometimes confusing, and difficult to use. –Many different distributions, no clear “perfect” version.