os lec01 intro

8/8/2019 OS Lec01 Intro

http://slidepdf.com/reader/full/os-lec01-intro 1/21

1

Operating System Concepts

Fall 2010

Kamran Siddique



2

Instructor Brief:

Kamran Siddique MS (Computer Engineering)

University of Engineering and Technology, Taxila

MCS, University of Arid Agriculture Rawalpindi

Contact Details:

Cell: 0788407733

[email protected]



3

Pre-requisite

Required: Introduction to computer

Programming concepts

Recommended:

Computer organization & Assemblylanguage

Algorithms & Data Structures



4

R ecommended R eading:

Operating System Concepts, by Silberchatz

A, Peterson J and Galvin P. Addison Wesley.

³Modern Operating Systems´ by Andrew S.

Tanenbaum. Prentice Hall pubs. RichardStevens,



Course Objectives:

To provide you with a general understandingof how computer works.

To explain the structure and functions of anoperating system.

Studying OS design IS studying design of large software systems.

OS is needed to make hardware useful.

To interact with computer hardware moreefficiently.

To prepare you for future courses.



The Course is NO T about:

Any particular operating system.

System administration.

Installation/trouble shooting of operating

system.



W hat is an Operating System (OS)?

A program that acts as an intermediarybetween a user of a computer and the

computer hardware.

Operating system goals: Execute user programs and make solving user

problems easier.

Make the computer system convenient to use.

Use the computer hardware in an efficientmanner.



Computer System Components:

1.Hardware ± provides basic computingresources (CPU, memory, I/O devices).

2.Operating system ± controls and coordinatesthe use of the hardware among the various

application programs for the various users.

3.Applications programs ± define the ways inwhich the system resources are used to solvethe computing problems of the users(compilers, database systems, video games,business programs).

4.Users (people, machines, other computers).



Abstract view of system components:



Processor:

Two internal registers

Memory address register (MAR)

Specifies the address for the next read or write

Memory buffer register (MBR) Contains data written into memory or receives

data read from memory

I/O address register

I/O buffer register



Top level components:



Processor R egisters:

User-visible registers

Which user can access and also can control their

operation.

Control and status registers

Used by processor to control operating of the

processor

Used by operating-system routines to control the

execution of programs



User visible registers:

May be referenced by machine language

Available to all programs - application

programs and system programs

Types of registers Data

Address

Index

Segment pointer

Stack pointer



Control & Status registers:

Program Counter (PC) Contains the address of an instruction to be

fetched

Instruction Register (IR) Contains the instruction most recently fetched

Program Status Word (PSW)

Condition codes

Interrupt enable/disable

Supervisor/user mode



Control & Status registers cont«

Condition Codes or Flags

Bits set by the processor hardware as a result of

operations

Examples

Positive result

Negative result

Zero

Overflow



Instruction Execution:

Two steps

Processor reads instructions frommemory

Fetches

Processor executes each instruction



Instruction Cycle:



Instruction Fetch & Execute:

The processor fetches the instruction frommemory

Program counter (PC) holds address of theinstruction to be fetched next

Program counter is incremented after eachfetch



Instruction R egister:

Fetched instruction is placed in the instructionregister

Categories Processor-memory

Transfer data between processor and memory

Processor-I/O Data transferred to or from a peripheral device

Data processing Arithmetic or logic operation on data

Control Alter sequence of execution



Characteristics of a Hypothetical Machine:



Example of Program Execution:

os lec01 intro

Documents