operating system software cs 1 rick graziani fall 2006

Operating System Software

CS 1

Rick Graziani

Fall 2006

Rick Graziani graziani@cabrillo.edu 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?

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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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What is an operating system (OS)?

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What is an operating system (OS)?

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The User’s View

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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

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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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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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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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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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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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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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Multitasking and Multiprocessing

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Single-user Operating Systems

• Windows XP

Only one user has access to the computer system at a time

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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

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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

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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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Virtual Memory

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Examples of Multiuser Operating Systems

Linux/UNIX • MAC OS X • Red Hat Linux• SUN UNIXMicrosoft NT, 2000 And many others, mostly on mainframes and minicomputers

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Advantages/Disadvantages of Multiuser Operating Systems

Advantages

• 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

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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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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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Command Line InterfaceDOS, UNIX, others

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DOS plus Windows 3.1

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Windows 95

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Windows XP

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Macintosh

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Mac OS X

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UNIX with X-Windows

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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

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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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Compatibility

QuestionWill 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.

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Order of Development

1. The CPU

2. Other Hardware Components

3. Operating System Software

4. Application Software

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Preemptive Multitasking vs Cooperative Multitasking

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

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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

Multiprocessing with Multiple CPU’s

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Microsoft Windows Operating Systems

• http://www.microsoft.com/windows/default.mspx

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Microsoft Windows Vista

• http://www.microsoft.com/windowsvista/default.mspx

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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.

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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.

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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.

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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.

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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.

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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.

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Linux

• http://www.linux.com/

• http://www.linux.org/

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www.linux.org

• 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).

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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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www.linux.org

• 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.

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www.linux.org

• 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.

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Organizing Files and Directories

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Organizing Files and Directories

Operating System Software

CS 1

Rick Graziani

Fall 2006