1. Operating System Software
CS 1
Rick Graziani
Fall 2006

2. Operating System Software
Why are operating system software so important?
Was Windows 95 a breakthrough for PCs? Why?
Why was Apple shopping for a new operating system and why did it decide on Mac OSX?
Why is Microsoft worried about Linux?
Rick Graziani

3. What is an operating system (OS)?
Operating System Software
Software which manages the overall operation of the computer system including:
hardware (CPU, RAM, I/O)
security
system interface
application interface
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4. What is an operating system (OS)?
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5. What is an operating system (OS)?
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6. The User’s View
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7. Rick Graziani graziani@cabrillo.edu

8. What “is” an operating system?
Software files (programs) which are stored on the hard disk
kernel with the internal programs
external programs
Supporting Data Files
Rick Graziani

9. The kernel
The operating system software file (program) which is copied into RAM, usually from the hard disk drive, during the boot-up.
The kernel remains in RAM while the computer is on and is in charge of the overall operation of the computer system.
The kernel contains the “internal programs” for the most often used operations like copying files.
kmem (Linux)
command.exe (Microsoft)
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10. The functions of an operating system
1. Manages and Interacts with Computer Hardware
2. Provides and Manages System Security
3. Provides the System Interface
4. Provides the Interface for Application Software
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11. 1. Manages and Interacts with Computer Hardware
Manages the CPU
- What software programs the
CPU works on and when
Manages RAM
- What is stored in RAM and
where it is stored
- Virtual memory
- OS will send message when
RAM is full
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12. 1. Manages and Interacts with Computer Hardware (continued)
Provides the interface for storage devices and manages how data is stored on those devices
- in charge of formatting disks
- creates sectors and clusters
- creates F.A.T. or V.T.O.C.
- sends message when disk is
full or there is some other
problem with writing data to
the disk
- virtual memory
- CD-ROM, DVD-ROM
- Flash drive
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13. 1. Manages and Interacts with Computer Hardware (continued)
Provides the Interface for Input and Output Devices
keyboard, mouse, printer,
device drivers = software programs which allow the hardware device to be used by the operating system and by application software
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14. Manages the CPU processing time and priority
Processing Applications
multitasking = ability of the operating system run multiple software programs (only one programs gets processed at a time)
multiprocessing = ability of the operating system to run multiple software programs at the same time
Number of users with simultaneous access
multiuser = ability of the operating system to allow multiple users access to the same computer at the same time
single user = the operating system only allows a single user at a time access to the computer
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15. Multitasking and Multiprocessing
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16. Single-user Operating Systems
Windows XP
Only one user has access to the computer system at a time
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17. Multiuser Operating Systems
Found on mainframes, minicomputers and microcomputers
Terminals or other computers (PCs, Macs) connected to the server
server = a computer which processes information (CPU and RAM) , stores information (hard disk), and/or provides access to peripheral devices (printers) for multiple users
Rick Graziani

18. The OS also plays a part!
Amount of RAM recognized by the Operating System
Windows 95: 1GB
Windows 98: 1GB
Windows 98SE: 1GB
Windows ME: 1.5GB
Windows NT: 4GB
Windows 2000 Professional: 4GB
Windows XP Home: 4GB
Windows XP Professional: 4GB
OS X: 8GB due to current hardware limitations
OS 9.x: 1.5GB (no single application can utilize more than 1GB)
Linux: 64GB
Rick Graziani

19. Virtual Memory
Virtual Memory (VM) = the ability of the CPU and the operating system software to use the hard disk drive as additional RAM when needed (safety net)
Good – no longer get “insufficient memory” error
Bad - performance is very slow when accessing VM
Solution = more RAM
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20. Virtual Memory
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21. Examples of Multiuser Operating Systems
Linux/UNIX
MAC OS X
Red Hat Linux
SUN UNIX
Microsoft NT, 2000
And many others, mostly on mainframes and minicomputers
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22. Advantages/Disadvantages of Multiuser Operating Systems
Central location for the installation and administration of all software and data
More cost effective - less expensive than multiple computers (PCs, Macs)
Disadvantages
Single source for possible problems
Loss of individual user control of their own software, data, and peripherals
Rick Graziani

23. 2. Provides and Manages System Security
Single-user Operating Systems
minimal security
user has full authority
Multiuser Operating Systems
login and password capability
protection of user’s data stored on the server’s central hard disk drives
protection and security for software programs
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24. 3. Provides the System Interface
System Interface or shell = the interface between the user and the computer
Command Line Interface (CLI)
UNIX, DOS, older OS’s
Graphical User Interface (GUI)
Macintosh OS, Windows 3.x, Windows 95, Windows XP, X-Windows, GNU, GNOME, Sun OS
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25. Command Line Interface DOS, UNIX, others
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26. DOS plus Windows 3.1
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27. Windows 95
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28. Windows XP
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29. Macintosh
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30. Mac OS X
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31. UNIX with X-Windows
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32. 4. Provides the Interface for Application Software
Operating systems are software
Operating systems are designed and developed for a specific CPU or “family of CPUs”
Macintosh OS: Motorola 680xx, PowerPC Gx, Intel
DOS: Intel CPUs
Windows 9x and XP: Intel 80386, 80486, and Pentium CPUs
Linux: Intel CPUs
MS NT & 2000: Intel CPUs
Rick Graziani

33. 4. Provides the Interface for Application Software (continued)
Application software is developed for an operating system
MS Word for Windows XP
Windows XP
Intel CPU
MS Word for the Macintosh
Macintosh OS X
Gx CPU or Intel CPU
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34. Compatibility Question
Will software developed for one operating system work on another? Will MS Word for Macintosh run on a PC with Windows XP?
Answer
No (unless there is special emulation software or hardware). The software must be developed separately for each operating system.
Much of this is beginning to change with MAC using the Intel CPU.
Rick Graziani

35. Order of Development 1. The CPU 2. Other Hardware Components
3. Operating System Software
4. Application Software
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36. Preemptive Multitasking vs Cooperative Multitasking
OS gives CPU processing time to other programs at a logical point, usually during idle time
Preemptive Multitasking
OS allocates CPU time between the different programs based on amount of time and priority of the software application
Rick Graziani

37. Multiprocessing with Multiple CPU’s
Asymmetric Multiprocessing = Tasks are assigned to a specific CPU and each CPU has its own RAM memory
Symmetric Multiprocessing = Tasks are assigned to any available CPU and CPU’s can share RAM memory
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38. Microsoft Windows Operating Systems
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39. Microsoft Windows Vista
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40. Glass and Animations
Windows are translucent, meaning that it's easier to focus on the content of a window rather than the window itself.
This feature (along with other window design enhancements on all Windows Vista computers) reduces distraction and streamlines your work while making windows easier to manage.
New scalable thumbnails are used throughout Windows to show you the actual first page for documents, the actual photo for photos, a screen capture for videos, and album art for individual songs.
Rick Graziani

41. Windows Sidebar
Windows Sidebar connects your desktop "gadgets"-mini-applications.
For example your gadgets might include local weather, a photo slideshow, a dictionary, news headlines.
Gadgets are organized in an easy-to-use panel-the Windows Sidebar-that discreetly docks on the side of your Windows desktop.
Rick Graziani

42. Folders & Virtual Folders
Virtual Folder, which is simply a saved search that is instantly run when you open the folder.
Subsequently, any time you click on this Virtual Folder, Windows Vista runs the search and provides results almost immediately.
Rick Graziani

43. Quick Search Box and Column Headers
The Explorer Quick Search box and Column Header controls help you efficiently narrow down large selections of data.
With the Quick Search Box, you can start typing the name or the first few letters of any displayed property, and the displayed files quickly filter down to just the matching terms.
The dynamic new Column Header drop down menus let you easily choose your filter values.
Rick Graziani

44. Reliability
Applications written for Windows Vista will keep running-with less chance of hanging or becoming unresponsive than with earlier versions of Windows.
Windows Vista is measurably more resilient to application problems and can recover better from problems that do occur.
Built-in diagnostics can proactively detect problems with system components such as hard disks, memory, and networks.
Rick Graziani

45. Security
Set of parental control features, providing powerful tools to help parents monitor, manage, and administer their children's computer usage to keep them safe.
User Account Protection which bridges the gap between user and administrative privileges by allowing you to run applications under a standard user account.
When you need to perform an administrative task, such as install software or drivers, Windows Vista prompts you to confirm your intentions or to provide your credentials.
Theft or loss of corporate intellectual property is an increasing concern for organizations.
Improved support for data protection at the document, file, directory, and machine level.
Rick Graziani

46. Linux http://www.linux.com/ http://www.linux.org/
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47.
Initially created as a hobby by a young student, Linus Torvalds, at the University of Helsinki in Finland.
Linus had an interest in Minix, a small UNIX system, and decided to develop a system that exceeded the Minix standards.
He began his work in 1991 when he released version 0.02 and worked steadily until 1994 when version 1.0 of the Linux Kernel was released.
The kernel, at the heart of all Linux systems, is developed and released under the GNU General Public License (GNU's Not Unix!', see recursive acronym).
Rick Graziani

48. www.linux.org Its source code is freely available to everyone.
It is this kernel that forms the base around which a Linux operating system is developed.
There are now literally hundreds of companies and organizations and an equal number of individuals that have released their own versions of operating systems based on the Linux kernel.
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49.
Apart from the fact that it's freely distributed, Linux's functionality, adaptability and robustness, has made it the main alternative for proprietary Unix and Microsoft operating systems.
IBM, Hewlett-Packard and other giants of the computing world have embraced Linux and support its ongoing development.
Rick Graziani

50.
More than a decade after its initial release, Linux is being adopted worldwide as a server platform primarily.
Its use as a home and office desktop operating system is also on the rise.
The operating system can also be incorporated directly into microchips in a process called "embedding" and is increasingly being used this way in appliances and devices.
Rick Graziani

51. Organizing Files and Directories
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52. Organizing Files and Directories
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53. Operating System Software
CS 1
Rick Graziani
Fall 2006