Introduction-1

CGS 3763Operating System Concepts

Spring 2004

Hal Stringer

Introduction-2

TODAY’S AGENDA

• Go over course syllabus.

• What is an operating system?

• Class make up - who’s enrolled– Major or Minor?

• Computer Science, IT or MIS

– Other computer science courses:

• CGS 1060 is minimum prerequisite

• CGS 3269 would be very helpful

– Programming experience will also be helpful although no programming projects required for this course

Introduction-3

SYLLABUS OVERVIEW

• Office Hours– Hal Stringer: CSB Rm 255– Mon. 1:30 – 2:30, Wed. 1:30 – 3:30 or by appointment.

• Email– stringer@cs.ucf.edu (include CGS3763 in subject line)– Be professional in your correspondence

• Website– http://www.cs.ucf.edu/courses/cgs3763/spring2004– Be sure to take notes in class

• Text Book– Operating System Concepts, Sixth Edition by Silberschatz,

Galvin and Gagne– http://cs-www.cs.yale.edu/homes/avi/os-book/osc

Introduction-4

SYLLABUS OVERVIEW (cont.)

• Class Times– Mon, Wed & Fri, 11:30 - 12:20, ENG2 Room 105

• Final Exam– Wednesday April 21, 10:00 - 12:50

– It will be comprehensive

• Other Dates– Jan. 9 End of Drop/Add (by 5:00)

– Jan. 19 Martin Luther King, Jr. Day, No classes.

– Feb. 27 Withdrawal Deadline

– Mar. 8-13 Spring Break, No classes.

– Apr. 19 Last Class

Introduction-5

SYLLABUS OVERVIEW (cont.)

• Attendance– Not taken but strongly encouraged

• Homework exercises will be assigned– Turned in during class.– Answers given in class only.

• Tests & Exams– Closed book, closed notes– T/F, Multi-Answer Multi-Choice, Problems, Essay– Simple calculators only

• Academic Behavior– Cheating or other forms of academic dishonesty will not be

tolerated

• Please turn off all cell phones and pagers in class.

Introduction-6

SYLLABUS OVERVIEW (cont.)

• Grading Based on:– Homework 5% (20 pts)– First Midterm 25% (100 pts)– Second Midterm 30% (120 pts)– Final Exam 40% (160 pts)

• Guaranteed Grading Scale:–   A 90 – 100% (360-400 pts)– B 80 – 89% (320-359 pts)– C 70 – 79% (280-319 pts)– D 60 – 69% (240-279 pts)– F Otherwise (< 240 pts)

• May use +/- or lower grading scale at my discretion.

Introduction-7

SYLLABUS OVERVIEW (cont.)

• Take advantage of multiple resources– Classroom lectures

– Required text book

– Lecture slides and review exercises

– Publishers web site and slides

– Use the internet or other text books

– See me during office hours or email

Introduction-8

COURSE CONTENT

• Not a course in Windows, Mac or Unix.

• Not a point & click, “how to” course.

• Instead we’ll look at the basic concepts that underlie these and other operating systems.– Processes & threads,

– CPU scheduling,

– memory and secondary storage management,

– protection and security,

– distributed systems

• Why?– Dispel some of the mystery - understand what happens when

you point and click.

– Learn new algorithms - many OS concepts can be applied to other disciplines.

Introduction-9

TENTATIVE COURSE CALENDAR

– Chapter 1 - Introduction– Chapter 2 - Computer System Structures– Chapter 3 - Operating System Structures– Chapter 4 - Processes– Chapter 5 - Threads

• First Midterm (around Feb 6th)

– Chapter 6 - CPU Scheduling– Chapter 7 - Process Synchronization– Chapter 8 - Deadlocks– Chapter 9 – Basic Memory Management

• Second Midterm (in March)

Introduction-10

TENTATIVE COURSE CALENDAR (cont.)

– Chapter 10 - Virtual Memory

– Chapter 11/12 - File Systems

– Chapter 14 - Mass Storage Structures

– Chapter 15/16/17 - Distributed Systems

– Chapter 18/19 - Protection and Security

• Final Exam (April 21)

Introduction-11

WHAT IS AN OPERATING SYSTEM?

• Definition varies depending on who you ask:– resource allocator

– master control program

– everything vendor ships with the computer

– program that is always running (kernel)

Introduction-12

WHAT IS AN OPERATING SYSTEM?

• For purposes of our class an operating system:1) is the interface or intermediary between a

user/application and the computer hardware

2) provides an environment in which the user can execute programs conveniently and

• application and/or system software

3) manages the computer’s resources efficiently

• memory, disk space, CPU time, I/O, software, etc.

• Often an OS is a tradeoff between convenience and efficiency– Windows (GUI) vs. Unix (command interpreter)

Introduction-13

OS AS INTERMEDIARY

• We’ll discuss hardware later in Chapter 2.

• What’s an application?– Software to accomplish a task

• Spread sheet, word processor, browser, email

– What about system software?

• Depending on who you ask, can be considered application programs, a computer resource, or part of the OS

Introduction-14

WHAT IS A PROCESS?

ALGORITHM

ASSEMBLEROR

COMPILER

PROGRAM

OBJECTCODE

LIBRARIES

LINKEREXECUTABLECODE

LOADER

PROBLEM

PROCESS

Introduction-15

WHAT IS A PROCESS (cont.)

• A process:– is a program in execution.

– has a process control block (PCB)

– has a program counter (PC)

• A process can have one or more threads.– A thread is sometimes known as a lightweight process

Introduction-16

RUNNING MULTIPLE PROGRAMS

• Parallel/Simultaneous Execution– Two or more processes performing the same activity at

the same time

– Requires two or more of the same resource (e.g., processors, printers, disk drives)

• Concurrent Execution– Two or more processes executing at the same time but

doing different activities

– Processes take turns using single shared resource

– Gives the illusion of parallel processing