Lecture No. 1
Operating Systems Concepts, Chapter 1
PowerPoint Slides for Lecture 1
Introduction and purpose of the course
Organization of a computer system
Purpose of a computer system
Requirements for achieving the purpose – Setting the stage for OS concepts and
Outline of topics to be discussed
What is an Operating System?
Organization of a Computer System
As shown in Figure 1.1, the major high-level components of a computer system are:
1. Hardware, which provides basic computing resources (CPU, memory, I/O
2. Operating system, which manages the use of the hardware among the various
application programs for the various users and provides the user a relatively
simple machine to use.
3. Applications programs that define the ways in which system resources are used
to solve the computing problems of the users (compilers, database systems, video
games, business programs).
4. Users, which include people, machines, other computers.
Figure 1.1. High-level components of a computer system
Purpose of a Computer—Setting the Stage for OS Concepts and Principles
Computer systems consist of software and hardware that are combined to provide a tool
to implement solutions for specific problems in an efficient manner and to execute
programs. Figure 1.2 shows the general organization of a contemporary computer system
and how various system components are interconnected.
Figure 1.2. Organization of a Computer System
Viewing things closely will reveal that the primary purpose of a computer system is
to generate executable programs and execute them. The following are some of the main
issues involved in performing these tasks.
1. Storing an executable on a secondary storage device such as hard disk
2. Loading executable from disk into the main memory
3. Setting the CPU state appropriately so that program