15 213 Introduction to Computer Systems Majd F Sakr and Khaled A Harras Computer Science Carnegie Mellon University Fall 2008 1 Organization Instructors Majd F Sakr msakr qatar cmu edu M1007 454 8625 Tue 3 5pm Khaled A Harras kharras qatar cmu edu M1020 454 8617 Thu 2 4pm TA Jackson Davis jcdavis andrew cmu edu Academic Resource Center ARC Mon 4 6pm Wed 12 30 2 30pm Please see the class Web page for up to date office hours Lecture Mon and Wed 8 30 9 50am M1030 Recitations Thu 8 30 9 20am M1032 Jackson Davis Class Web Page http www qatar cmu edu msakr 15213 f08 Class Message Board http autolab qatar cmu edu 15213 f08 Note This is the only message board your instructors will be monitoring We will not be using the Andrew or Blackboard message boards for this class 1 2 Objectives Learning Outcomes Our aim in CS 213 is to help you become a better programmer by teaching you the basic concepts underlying all computer systems We want you to learn what really happens when your programs run so that when things go wrong as they always do you will have the intellectual tools to solve the problem Why do you need to understand computer systems if you do all of your programming in high level languages In most of computer science we re pushed to make abstractions and stay within their frameworks But any abstraction ignores effects that can become critical As an analogy Newtonian mechanics ignores relativistic effects The Newtonian abstraction is completely appropriate for bodies moving at less than 0 1c but higher speeds require working at a greater level of detail Oversimplifying matters somewhat our 21x sequence works as follows 211 is based on a simplified model of program execution 212 builds further layers of abstraction 213 introduces greater detail about system behavior and operation This greater detail is needed for optimizing program performance for working within the finite memory and word size constraints of computers and for systems level programming The following realities are some of the major areas where the abstractions we teach in 211 212 break down 1 Int s are not integers Float s are not reals Our finite representations of numbers have significant limitations and because of these limitations we sometimes have to think in terms of bit level representations 2 You ve got to know assembly language Even if you never write programs in assembly The behavior of a program cannot be understood sometimes purely based on the abstraction of a high level language Further understanding the effects of bugs requires familiarity with the machine level model 3 Memory matters Computer memory is not unbounded It must be allocated and managed Memory referencing errors are especially pernicious An erroneous updating of one object can cause a change in some logically unrelated object Also the combination of caching and virtual memory provides the functionality of a uniform unbounded address space but not the performance 4 There is more to performance than asymptotic complexity Constant factors also matter There are systematic ways to evaluate and improve program performance 5 Computers do more than execute instructions They also need to get data in and out and they interact with other systems over networks By the end of the course you will understand these realities in some detail As a result you will be prepared to take any of the upper level systems classes at Carnegie Mellon both CS and ECE Even more important you will have learned skills and knowledge that will help you throughout your career 2 3 Textbook The primary textbook for the course is Randal E Bryant and David R O Hallaron Computer Systems A Programmer s Perspective Prentice Hall 2003 In addition we require you to have the following reference book on the C programming language Brian W Kernighan and Dennis M Ritchie The C Programming Language Second Edition Prentice Hall 1988 This the classic K R book the standard against which all reference manuals are compared It is an essential part of every computer scientist s library 4 Course Organization Your participation in the course will involve five forms of activity 1 Attending the lectures 2 Preparing for and participating in the recitations 3 Laboratory assignments 4 Reading the text 5 Exams Attendance will be taken at the lectures and recitation it will be worth 5 of your grade You will be considered responsible for all material presented at the lectures and recitations Lectures will cover higher level concepts Recitations will be more applied covering important how to s especially in using tools that will help you do the labs In addition the recitations will help clarify lecture topics and describe exam coverage The textbook contains both practice problems within the chapter text and homework problems at the end of each chapter The intention is that you work on the practice problems right as you are reading the book The answers to these problems are at the end of each chapter Our experience has been that trying out the concepts on simple examples helps make the ideas more concrete In addition the schedule at the end of this document and on the class web page shows specific homework problems with each lecture topic The intention is that you try these out and discuss them in the next recitation You will find that you will get much more out of recitation if you have done some advance preparation The only graded assignments in this class will be a set of seven labs Some of these are fairly short requiring just one week while others are more ambitious requiring several weeks 3 5 Getting Help For urgent communication with the teaching staff it is best to send electronic mail preferred or to phone If you want to talk to a staff member in person remember that our posted office hours are merely nominal times when we guarantee that we will be in our offices You are always welcome to visit us outside of office hours if you need help or want to talk about the course However we ask that you follow a few simple guidelines Prof Sakr normally works with his office door open and welcomes visits from students whenever his doors are open However if his door is closed he is busy with a meeting or a phone call and should not be disturbed Prof Harras normally works with his office door open and welcomes visits from students whenever his doors are open However if his door is closed he is busy with a meeting or a phone call and should not be disturbed Please send mail to arrange a meeting with your TA outside
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