Operating System Software CS 1 Rick Graziani Fall 2006

Rick Graziani 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 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

Rick Graziani What is an operating system (OS)?

Rick Graziani What is an operating system (OS)?

Rick Graziani The User’s View

Rick Graziani

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 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)

Rick Graziani 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

Rick Graziani 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

Rick Graziani 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

Rick Graziani 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

Rick Graziani 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

Rick Graziani Multitasking and Multiprocessing

Rick Graziani Single-user Operating Systems Windows XP Only one user has access to the computer system at a time

Rick Graziani 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 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 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

Rick Graziani Virtual Memory

Rick Graziani 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

Rick Graziani 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

Rick Graziani 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

Rick Graziani 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

Rick Graziani Command Line Interface DOS, UNIX, others

Rick Graziani DOS plus Windows 3.1

Rick Graziani Windows 95

Rick Graziani Windows XP

Rick Graziani Macintosh

Rick Graziani Mac OS X

Rick Graziani UNIX with X-Windows

Rick Graziani 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 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

Rick Graziani 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 Order of Development 1. The CPU 2. Other Hardware Components 3. Operating System Software 4. Application Software

Rick Graziani 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

Rick Graziani 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

Rick Graziani Microsoft Windows Operating Systems

Rick Graziani Microsoft Windows Vista

Rick Graziani 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 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 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 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 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 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 Linux

Rick Graziani 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 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.

Rick Graziani 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 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 Organizing Files and Directories

Rick Graziani Organizing Files and Directories

Operating System Software CS 1 Rick Graziani Fall 2006