This document provides an introduction to operating system concepts. It discusses what an operating system is, including that it hides hardware details and manages resources. It also categorizes different types of operating systems like mainframe, server, personal computer, and real-time operating systems. The document reviews computer hardware components and operating system structures like processes, file systems, and system calls.

1. 1
Introduction
Chapter 1
1.1 What is an operating system
1.2 The operating system zoo
1.3 Computer hardware review
1.4 Operating system concepts
1.5 System calls
1.6 Operating system structure

2. 2
Introduction
• A computer system consists of
– hardware
– system programs
– application programs

3. 3
What is an Operating System
• It is an extended machine
– Hides the messy details which must be performed
– Presents user with a virtual machine, easier to use
• It is a resource manager
– Each program gets time with the resource
– Each program gets space on the resource

4. 4
The Operating System Zoo
• Mainframe operating systems
– Processing many jobs at once
– Three kinds of services
• Batch
– Processes routine jobs without any interactive user present
• Transaction processing
– Handle large numbers of small requests
• Timesharing
– Allow multiple remote users to run jobs on the computer at once, such as
querying a big database
• Server operating systems
– Serve multiple users at once over a network and allow
the users to share hardware and software resources.
– Print service, file service, or Web service

5. • Multiprocessor operating systems
– Connect multiple CPUs into a single system.
– Special features
• Communication and connectivity
• Personal computer operating systems
• Real-time operating systems
– Hard Real-time OS
– Soft Real-time OS
• Embedded operating systems
– size, memory, and power restrictions
• Smart card operating systems
5

6. 6
Computer Hardware
• Components of a simple personal computer
Monitor
Bus

7. 7
(a) A three-stage pipeline
(b) A superscalar CPU

8. 8
• Typical memory hierarchy
– numbers shown are rough approximations

9. 9
Structure of a disk drive

10. 10
One base-limit pair and two base-limit pairs

11. 11
(a) Steps in starting an I/O device and getting interrupt
(b) How the CPU is interrupted
(a) (b)

12. 12
Operating System Concepts
• A process tree
– A created two child processes, B and C
– B created three child processes, D, E, and F

13. 13
File system for a university department

14. 14
• Before mounting,
– files on floppy are inaccessible
• After mounting floppy on b,
– files on floppy are part of file hierarchy

15. System Call
• Interface between the operating system and
the user programs.
15

16. 16
Steps in Making a System Call
There are 11 steps in making the system call
read (fd, buffer, nbytes)

17. 17
Some System Calls For Process Management

18. 18
Some System Calls For File Management

19. 19
Some System Calls For Directory Management

20. 20
Some System Calls For Miscellaneous Tasks

21. 21
System Calls
• Processes have three segments: text, data, stack

22. 22
System Calls
(a) File system before the mount
(b) File system after the mount

23. 23
Win32 API Calls

24. 24
Monolithic system

25. 25
THE operating system

26. 26
VM/370 with CMS

27. 27
Client-server model

28. 28
Client-server model in a
distributed system