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Note for Operating Systems - OS by Vssut Rulers

  • Operating Systems - OS
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  • Veer Surendra Sai University Of Technology VSSUT -
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Operating System TEXT BOOK: 1. Operating System Concepts – Abraham Silberschatz, Peter Baer Galvin, Greg Gagne, 8th edition, Wiley-India, 2009. 2. Mordern Operating Systems – Andrew S. Tanenbaum, 3rd Edition, PHI 3. Operating Systems: A Spiral Approach – Elmasri, Carrick, Levine, TMH Edition REFERENCE BOOK: 1. Operating Systems – Flynn, McHoes, Cengage Learning 2. Operating Systems – Pabitra Pal Choudhury, PHI 3. Operating Systems – William Stallings, Prentice Hall 4. Operating Systems – H.M. Deitel, P. J. Deitel, D. R. Choffnes, 3rd Edition, Pearson 1|Page

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Operating System: An operating system is a program which manages all the computer hardwares. It provides the base for application program and acts as an intermediary between a user and the computer hardware. The operating system has two objectives such as:  Firstly, an operating system controls the computer‘s hardware.  The second objective is to provide an interactive interface to the user and interpret commands so that it can communicate with the hardware. The operating system is very important part of almost every computer system. Managing Hardware The prime objective of operating system is to manage & control the various hardware resources of a computer system. These hardware resources include processer, memory, and disk space and so on. The output result was display in monitor. In addition to communicating with the hardware theoperating system provides on error handling procedure and display an error notification. If a device not functioning properly, the operating system cannot be communicate with the device. Providing an Interface The operating system organizes application so that users can easily access, use and store them. 2|Page

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It provides a stable and consistent way for applications to deal with the hardware without the user having known details of the hardware. If the program is not functioning properly, the operating system again takes control, stops the application and displays the appropriate error message. Computer system components are divided into 5 parts  Computer hardware  operating system  utilities  Application programs  End user The operating system controls and coordinate a user of hardware and various application programs for various users. It is a program that directly interacts with the hardware. The operating system is the first encoded with the Computer and it remains on the memory all time thereafter. System goals The purpose of an operating system is to be provided an environment in which an user can execute programs. Its primary goals are to make the computer system convenience for the user. Its secondary goals are to use the computer hardware in efficient manner. 3|Page

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View of operating system User view:The user view of the computer varies by the interface being used. The examples are -windows XP, vista, windows 7 etc. Most computer user sit in the in front of personal computer (pc) in this case the operating system is designed mostly for easy use with some attention paid to resource utilization. Some user sit at a terminal connected to a mainframe/minicomputer. In this case other users are accessing the same computer through the other terminals. There user are share resources and may exchange the information. The operating system in this case is designed to maximize resources utilization to assume that all available CPU time, memory and I/O are used efficiently and no individual user takes more than his/her fair and share.The other users sit at workstations connected to network of other workstations and servers. These users have dedicated resources but they share resources such as networking and servers like file, compute and print server. Here the operating system is designed to compromise between individual usability and resource utilization. System view: From the computer point of view the operating system is the program which is most intermediate with the hardware. An operating system has resources as hardware and software which may be required to solve a problem like CPU time, memory space, file storage space and I/O devices and so on. That‘s why the operating system acts as manager of these resources. Another view of the operating system is it is a control program. A control program manages the execution of user programs to present the errors in proper use of the computer. It is especially concerned of the user the operation and controls the I/O devices. Types of Operating System 1. Mainframe System: It is the system where the first computer used to handle many commercial scientific applications. The growth of mainframe systems traced from simple batch system where the computer runs one and only one application to time shared systems which allowed for user interaction with the computer system a. Batch /Early System: Early computers were physically large machine. The common input devices were card readers, tape drivers. The common output devices were line printers, tape drivers and card punches. In these systems the user did not interact directly with the computer system. Instead the user preparing a job which consists of programming data and some control information and then submitted it to the computer 4|Page

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