1. CALTECH CS24 Spring 2004 -- DeHon CS24: Introduction to Computer Systems Day 1: March 29, 2004 Introduction and Overview

2. CALTECH CS24 Spring 2004 -- DeHon Today What Who Why What Detail (Overview) How (Course Details)

3. CALTECH CS24 Spring 2004 -- DeHon What How the computer works below the programming language –(mostly above the physics) How processor is organized –How your computation is actually performed Why is there an Operating System –And what does it do for you?

4. CALTECH CS24 Spring 2004 -- DeHon What What lies between the –Programming Language –Physics Abstraction Stack

5. CALTECH CS24 Spring 2004 -- DeHon What New class –First time being taught here Only course in CS undergraduate core that actually deals with computers as physical machines Dynamics / typical case How we manage computer systems –Coordinate shared resources –Not just one program How do we deal with technology –Technology change

6. CALTECH CS24 Spring 2004 -- DeHon Who? Two Instructors –Jason Hickey represent high-level view What does the Programmer want? –André DeHon Represent the low-level view What does the hardware want? –How does it perform well?

7. CALTECH CS24 Spring 2004 -- DeHon Who? TAs: –Michael Wrighton –Cristian Tapus

8. CALTECH CS24 Spring 2004 -- DeHon Why? (low road) As programmers: want to understand your tool. –How does it work? –When does it break? –What are those constants we kept ignoring in CS20, CS38? –How do you get the most out of it? Why is this a challenge?

9. CALTECH CS24 Spring 2004 -- DeHon Why? As innovators: want to understand the prior art –How does it work? –What’s wrong with it? –How can we make it better?

10. CALTECH CS24 Spring 2004 -- DeHon Why? (high road) What problems does it solve? –What are the big ideas that makes this work? Is the Instruction Set Architecture (ISA) abstraction necessary? Isolation? Virtualization? …

11. CALTECH CS24 Spring 2004 -- DeHon Why? (Future) This will all break down in the next 10-20 years. –Low-end: Approaching Atomic scale Time to pay attention to low-level physics –Sequential processor at end of scaleable life –High-end: Scale of modern systems/software already stressing (breaking?) model How do we enable bigger systems? In critical roles? Reduce human time?

12. CALTECH CS24 Spring 2004 -- DeHon Why? (Future) This will all break down in the next 10-20 years. We’re going to have to rebuild it. –What were the good/high-level ideas we need to keep? Can and should be transferred? You: –May need to help lead the transition –At least need to understand the big ideas to survive the transition

13. CALTECH CS24 Spring 2004 -- DeHon Why? We are not learning this to pay homage to –Bill Gates –Dennis Richie, Ken Thompson –Linus Torvalds –Fred Brooks, Gene Amdahl –John Hennessey, Dave Patterson –Bob Colwell Learning this so we can move forward while not repeating the mistakes of the past –Keep the good ideas –Discard the bad ones –Solve problems they didn’t need to…

14. CALTECH CS24 Spring 2004 -- DeHon Back to What

15. CALTECH CS24 Spring 2004 -- DeHon Physics Ultimately, we can build machines which compute because the physical world computes –  F=0,F=ma, F=-kx, … –  I=0,V=IR,  V=(I  T)/C, I d =I s (e [qv/kt] -1)

16. CALTECH CS24 Spring 2004 -- DeHon Devices From these phenomena we can build useful devices –Store charge  store value –Switch current based on value

17. CALTECH CS24 Spring 2004 -- DeHon Gates From these devices we can build gates

18. CALTECH CS24 Spring 2004 -- DeHon Boolean Logic From gates we can build any particular boolean function –E.g. o=(a+/b)(b+c)+/b*/c Day 2

19. CALTECH CS24 Spring 2004 -- DeHon Universal Turing Machine From CS21 (CS20), you know we can, in theory, –build a machine which will emulate any other machines –A Universal Machine…

20. CALTECH CS24 Spring 2004 -- DeHon Programmable Logic Likewise, we can build collections of gates which will perform any function

21. CALTECH CS24 Spring 2004 -- DeHon Programmable Machine …and ultimately, a machine which can perform (almost) any computable function Week 2

22. CALTECH CS24 Spring 2004 -- DeHon How Organize Programmable Machine? Theory tells us that we can build such a machine? Engineering asks how we should build such a machine

23. CALTECH CS24 Spring 2004 -- DeHon What’s in here?

24. CALTECH CS24 Spring 2004 -- DeHon Raw Machine Even this is pretty raw –add, or, xor, ld, st, br How do we make it usable? Invent conventions: –Using memory –Representing data –Making procedure calls

25. CALTECH CS24 Spring 2004 -- DeHon Runtime Systems Over time, we build up a collection of software necessary to run the machine –Load program –Allocate/deallocate memory –Perform I/O –Handle asynchronous events –…–…

26. CALTECH CS24 Spring 2004 -- DeHon It might be nice if… Could run more than one program All the programs didn’t need to know about each other Could run more than one program at a time –Didn’t require a physical processor for each program want to run Could use more memory than you have physical RAM Could communicate with other programs

27. CALTECH CS24 Spring 2004 -- DeHon It might be nice if… One program crashing didn’t crash the machine Could monitor a running (crashed) program Could share the machine amongst people (programs) that don’t necessarily know about or trust each other…

28. CALTECH CS24 Spring 2004 -- DeHon Operating System …we need some way to virtualize and manage our physical resources This is what an Operating System provides Most of our programs run in the context of an operating system and an instruction set processor –API: Application Programming Interface

29. CALTECH CS24 Spring 2004 -- DeHon What What lies between the –Programming Language –Physics Abstraction Stack

30. CALTECH CS24 Spring 2004 -- DeHon How

31. CALTECH CS24 Spring 2004 -- DeHon Course Components Text (CS:APP) Lectures Recitations –Fri. 4pm here –Also Fri. 2pm (TBD) Homework –9 weekly labs Midterm, final Grade:  70% for best 8 of 9 labs  10% midterm  20% final

32. CALTECH CS24 Spring 2004 -- DeHon Resources Course Web Page Administrative handout –Give you all of these details Mailing Lists Forum Computer Accounts

33. CALTECH CS24 Spring 2004 -- DeHon Pragmatics Programming in C and Assembly –First recitation on C –Text has asides for “new” C programmers –…will learn assembly bottom up –…will help C, since C is so close to assembly… Online submission systems

34. CALTECH CS24 Spring 2004 -- DeHon Feedback Sheets Please fill one out each class –anonymous New course –Need to understand what works –So can improve for future lectures –So can improve for future years

35. CALTECH CS24 Spring 2004 -- DeHon You Action Items Get book Read chapter 1 Find web page Read administrative handout –Signup for mailing list, find forum Get computer account –If don’t already have one Read Assignment 1 –Pickup support code

36. CALTECH CS24 Spring 2004 -- DeHon Big Ideas Valuable not to program physics directly –(most of the time…) Abstraction hierarchy –From programming language to physics Valuable to abstract and share resources Need to Understand Hierarchy –to make the most of machines –to improve/re-invent

37. CALTECH CS24 Spring 2004 -- DeHon Questions