Chapter 1: Introduction to oerating system TOPICS Computer & Software Operating System Strategies Learning Objectives: Introduction to OS basic and fundamentals The key element in OS Environment in OS Learning Outcomes: Student able to identify key component in OS Student able to know OS strategies

Why studying OS To extract the best performance from OS To understand how to use the system functionality most effective To understand and exploit design during program execution

Computer system & Software Hardware Provide tool to solve specific problems To solve specific problem Application Software provide general programming environment to create application needs. OS is subset of syst. sw System Software

Differences between Syst. Software and Application Software System Software Application Software Supports the use in computer operations Manages computer machine resources such as register,CPU, I/O syst Written in Low level language. Eg: assembly language Used as long as computer is turned on. Performs more than one job or task related at a time(multitasking) Control many processes at a time Concern problem solving and the use of computer as a tools Manages operation data such as insert, delete, update and sorting. Written in high level language such as Pascal, C++,VB, Java Use only when it’s needed Performs only one job or task at a Process done by following step by step at a time.

Function OS Interface between hardware and user which is responsible for the management. To coordinate of activities and the sharing of the resources of a computer, that acts as a host for computing. Eg: Programmer use OS to implement application software To handle the resource allocation an access protection of the hardware. to provide maintain a platform for running application software Example OS: MS Dos, Ms Windows, Mac OS, Linux and Unix

OS Strategies Batch Processing Timesharing Personal Computers & workstation Process Control & real time computers Network Technology

1. Batch Processing Set of jobs is submitted in sequence for processing. These systems have a relatively long average turnaround period (interval from arrival time to completion) for jobs.

1. Batch Processing Services a collection of jobs called a batch Jobs: unit of work submitted by a user to the OS. A job usually consists of a program and the data to be run. Jobs are stored in job queues until the computer is ready to process them. There is no interaction between the user and the computer while the program is being run. Computers which do batch processing often operate at night. Only one program can be run during one cycle.(not multiuser program) Example : Payroll - when a company calculates the wages for its workforce and prints payslips.

2. Time Sharing Called as interactive system or conversation. Support multiple user. Called as interactive system or conversation. Basic functions and facilities in a time sharing system: a) Users can access main memory at the same time. Time sharing system supposedly to keep each of the memory space for each users and provide equal time allocation for each processor b) Processor has to be able do multitasking by having interuptablity. Eg: mainframe and mini computers are time sharing systems.

3. Personal computers and workstations A workstation is a high-end microcomputer higher performance than Personal Computer (CPU and graphics, memory capacity and multitasking capability) multi-user sharing of a single computer toward an environment. These single-user machines are multiprogrammed so that the computer can be performing several different tasks concurrently on behalf of the user.

Inexpensive and easy to install in any location. MINICOMPUTER First generation Digital Equipment Corporation (DEC) PDP-8 on display at the National Museum of American History MICROCOMPUTER The Commodore 64 was one of the most popular microcomputers of its era, and is the best-selling model of home computer of all time.[1] http://en.wikipedia.org/wiki/Microcomputer

4. Process control and real-time computers used to control “autonomous systems” such as hydroelectric dams, satellites, and robots. This multiprogramming OS is required to guarantee response time for particular computing tasks Example: Automatics System, Airplane Computer System, Online Bank System

5. Network technology Modern computer configurations use high- speed networks to interconnect groups of personal computers, workstations, batch system, timesharing systems, and sometimes even real-time systems. Need for resources and information sharing across the network

references Nutt Gary Operating System : A modern perspective , Addison Wesley.