CS 213: Introduction to Computer SystemsRandal E. Bryant(*) and David R. O’Hallaron(**)(*) School of Computer Science(**) School of Computer Science and Dept of Electrical and Computer EngineeringCarnegie Mellon UniversityFall 19991. OrganizationInstructors:Randal E. Bryant David R. O’HallaronWeH 7128 WeH 8125x8-8821 [email protected] [email protected] 10:30–11:30am Tue 10:30–11:30amTAs:Khalil Amiri Jeff Pierce Sanjay Rao Seggy UmbohWeH 8114 WeH 4114 WeH 8208 Wean Clusterx8-3056 x8-3075 x8-1425 [email protected] [email protected] [email protected] [email protected], 4:00–5:00pm Wed, 3:00-4:00pm Wed, 2:00–3:00pm Wed, 5-6pmClass Secretary:Joan MaddammaWeH [email protected]:Tue Thu 9:00-10:20, Wean Hall 7500Recitations:A Mon 10:30–11:20 OSC (Old Student Center) 203 Sanjay RaoB Mon 11:30–12:20 OSC (Old Student Center) 203 Khalil AmiriC Mon 12:30–1:20 OSC (Old Student Center) 203 Jeff PierceD Mon 1:30–2:20 OSC (Old Student Center) 203 Seggy UmbohWeb page: www.cs.cmu.edu/afs/cs/academic/class/15213-f99/www/Newsgroup: cmu.cs.class.cs21312. ObjectivesOur aim in CS 213is to help you become a better programmerby teaching you the basic concepts underlyingall computer systems. We want you to learn what really happens when your programs run, so that whenthings go wrong (as they always do) you will have the intellectual tools to solve the problem.Whydoyouneedtounderstandcomputersystemsif you do allof your programmingin 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 ignoresrelativistic effects. The Newtonian abstraction is completely appropriate for bodies moving at less than0.1c, but higher speeds require working at a greater level of detail.Our 21X sequence works as follows: 211 is based on a simplified model of program execution. 212 buildsfurther layers of abstraction. 213 introducesgreater detailabout system behavior and operation. This greaterdetail is needed for optimizing program performance, for working within the finite memory and word sizeconstraints of computers, and for systems-level programming.The following "realities" are some of the major areas where the abstractions we teach in 211/212 breakdown:1. Int’s are not integers, Float’s are not reals. Our finite representations of numbers have signifi-cant limitations, and because of these limitations we sometimes have to think in terms of bit-levelrepresentations.2. You’vegot to knowassembly language. Evenif younever write programsin assembly, The behaviorofa 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. Memoryreferencing errors are especially pernicious. An erroneous updating of one object can cause a changein some logically unrelated object. Also, the combination of caching and virtual memory providesthe 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 aresystematic ways to evaluate and improve program performance5. Computers do more than execute instructions. They also need to get data in and out and they interactwith other systems over networks.By the end of the course you will understand these “realities” in some detail. As a result, you will beprepared to take any of the upper level systems classes at Carnegie Mellon. Even more important, you willhave learned skills and knowledge that will help you throughout your career.Good luck!3. TextbookCS 213 is a unique course for which no complete textbook exists. In fact, during this semester, yourinstructors will be preparing the alpha version of a new textbook, in the form of class notes, that we expectto be published sometime next year. We’ll hand out the notes to you as we write them up. We’d reallyappreciate your comments and criticisms.In the interim, the following will serve as the text for the course:2Samuel P. Harbison and Guy L. Steele Jr., C: A Reference Manual, Fourth Edition, PrenticeHall, 1995.4. Course OrganizationYour participation in the course will involve five forms of activity:1. Attending the lectures.2. Participating in the recitations.3. Homework and laboratory assignments.4. Reading the text and supplementary handouts.5. ExamsAttendance will not be taken at the lectures or recitation sections. You will be considered responsible forall material presented at the lectures and recitations. Lectures will cover higher-level concepts. Recitationswill 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.There will be two types of assignments in this class. Lab assignments will be multi-week efforts (in groupsof up to 2) providing in-depth understanding of some aspect of computer systems. Labs will involve somecombination of C and assembly programming, and some will involve performance measurements. Labswill always be handed out in class on Thursday and due a couple of weeks later on a Wednesday.Homework assignments will be 1-week efforts (that you work on individually) that involve solving a seriesof smaller problems. The solution to many of these will involve writing small C programs. Homeworks aredesigned to be drills to help you get practice for exam problems. Homeworks will always be handed out atclass on Tuesday and due the following Monday.5. Getting helpFor 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 timeswhen we guarantee that we will be in our offices. You are always welcome to visit us outside of office hoursif you need help or want to talk about the course. However, we ask that you follow a few simple guidelines:Prof. Bryant and Prof. O’Hallaron normally work with their office doors open and welcome visitsfrom students whenever their doors are open. However, if their doors are closed, they are busy with ameeting or a phone call and should not be disturbed.The
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