INFORMATION SYSTEM-SOFTWARE Topic: OPERATING SYSTEM CONCEPTS

OBJECTIVES To define the term Operating System To discuss the historic overview of O/S Types of Operating Systems Interpret the basic functions of Operating System

GOALS OF AN OPERATING SYSTEM To make the computer system convenient to use. To use the computer hardware in an efficient manner.

PURPOSE OF AN OPERATING SYSTEM The purpose of an operating system is to provide an environment in which a user may execute programs.

Users Application Programs Operating system Computer Hardware Abstract view of the components of a computer system

WHAT IS AN OPERATING SYSTEM? An Operating System is an interface between user and hardware of a computer system.

WHAT IS AN OPERATING SYSTEM? An Operating System is a system software which may be viewed as an organized collection of software consisting of procedures for operating a computer and providing an environment for execution of programs.

OTHER DEFINITIONS An Operating System is a control program. An Operating System is similar to a Government. An Operating System can be defined as a Resource Manager.

HISTORICAL VIEW OF AN OPERATING SYSTEM Early systems: In the early systems, no Operating System programs runs on a base machine.

HISTORICAL VIEW OF AN OPERATING SYSTEM Simple Monitor: Monitor programs were developed that allowed users to “batch” their jobs together, which constituted an automatic job sequencing.

HISTORICAL VIEW OF AN OPERATING SYSTEM Offline Operation: As computers became more complex, especially with regard to I/O device management, offline operating systems were developed that permanently resided in memory and provided I/O Control Services for user jobs.

HISTORICAL VIEW OF AN OPERATING SYSTEM Buffering and Spooling: More ways to overlap CPU with slower operations. Buffering:- overlap computing with I/O for same job. Spooling:- overlap computing with I/O for different jobs.

HISTORICAL VIEW OF AN OPERATING SYSTEM Multiprogramming: Multiprogramming was used as a technique to enhance the throughput efficiency. Overlapping interleaving computing of different jobs. More than one job is “ready” at the same time.

SPOOLING: DISK CARD READER LINE PRINTER CPU

Different types of Multiprogramming Operating System Multitasking operating system Multiprocessing operating system Multi-user operating system

TIMESHARING AND REAL-TIME SYSTEMS Timesharing system: This executes commands of several users as they are entered, attempting to provide each user with a reasonably short response time to each command.

TIMESHARING AND REAL-TIME SYSTEMS Real-time system: It is designed to respond quickly to external signals such as those generated by data sensors.

FUNCTIONS OF OPERATING SYSTEM Memory management Process management Device management Information management Protection Error Handling      

FUNCTIONS OF OPERATING SYSTEM Memory management Process management Device management Information management Protection Error Handling       The o/s keeps track of the memory, what parts are in use and by whom.

FUNCTIONS OF OPERATING SYSTEM Memory management Process management Device management Information management Protection Error Handling       The o/s keeps track of processors and the status of processes. It decides who will have a chance to who will have a chance to use the processor.

FUNCTIONS OF OPERATING SYSTEM Memory management Process management Device management Information management Protection Error Handling       The o/s keeps track of the devices, channels, control units and decides what is an efficient way to allocate the device.

FUNCTIONS OF OPERATING SYSTEM Memory management Process management Device management Information management Protection Error Handling       O/S keeps track of the information, its location, use, status etc. and decides who gets use of the resources, enforce protection requirements.

FUNCTIONS OF OPERATING SYSTEM Memory management Process management Device management Information management Protection Error Handling       An o/s is to protect the user from unauthorized access from unauthorized access of his files or data. And also it should protect itself from users itself from users

FUNCTIONS OF OPERATING SYSTEM Memory management Process management Device management Information management Protection Error Handling       An o/s must respond to errors by taking the appropriate actions.

FILE CONCEPT File is a collection of related information. It is named and is referred by its name. Files are organized into directories for easy access.

DIRECTORY STRUCTURE ROOT D0 F1 D3 D2 D21D31 F311 F31 F21 D1 D311

CLIENT-SERVER MODEL User process(client process) sends the request to a server process, which when does the work and sends back the answer.

CLIENT-SERVER ARCHITECTURE CLIENT is an application that runs on a personal computer or on a workstation and relies on SERVER to perform some operations such as managing files, disk drives, printers or network traffic.

NETWORK OPERATING SYSTEM The Software that enhances a basic Operating System by adding Networking Features. Examples: Novell Netware, WINDOWS NT

DISTRIBUTED OPERATING SYTEM Distributed operating system is one that looks to its users like an ordinarily centralized operating system but runs on multiple independent CPU’s. Key concept is TRANSPARENCY.

Operating system is an essential component of system software which consists of procedures for managing computer resources. Operating system functions primarily includes Memory, Process,Device, File management. SUMMARY: