1. CS24: Introduction to Computer Systems
Day 1: March 29, 2004
Introduction and Overview
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2. Today What Who Why What Detail (Overview) How (Course Details)
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3. 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?
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4. What What lies between the Abstraction Stack Programming Language
Physics
Abstraction Stack
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5. 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
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6. Who? Two Instructors Jason Hickey André DeHon
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?
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7. Who? TAs: Michael Wrighton Cristian Tapus
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8. 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?
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9. Why? As innovators: want to understand the prior art How does it work?
What’s wrong with it?
How can we make it better?
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10. 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? …
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11. 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?
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12. 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
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13. 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…
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14. Back to What
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15. Physics SF=0,F=ma, F=-kx, … SI=0,V=IR, DV=(I DT)/C,
Ultimately, we can build machines which compute because the physical world computes
SF=0,F=ma, F=-kx, …
SI=0,V=IR, DV=(I DT)/C,
Id=Is(e[qv/kt]-1)
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16. Devices From these phenomena we can build useful devices
Store charge  store value
Switch current based on value
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17. Gates From these devices we can build gates
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18. Boolean Logic From gates we can build any particular boolean function
E.g. o=(a+/b)(b+c)+/b*/c
Day 2
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19. Universal Turing Machine
From CS21 (CS20), you know we can, in theory,
build a machine which will emulate any other machines
A Universal Machine…
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20. Programmable Logic
Likewise, we can build collections of gates which will perform any function
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21. Programmable Machine
…and ultimately, a machine which can perform (almost) any computable function
Week 2
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22. How Organize Programmable Machine?
Theory tells us that we can build such a machine?
Engineering asks how we should build such a machine
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23. What’s in here?
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24. Raw Machine Even this is pretty raw How do we make it usable?
add, or, xor, ld, st, br
How do we make it usable?
Invent conventions:
Using memory
Representing data
Making procedure calls
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25. 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 …
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26. 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
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27. 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…
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28. 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
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29. What What lies between the Abstraction Stack Programming Language
Physics
Abstraction Stack
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30. How
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31. Course Components Text (CS:APP) Lectures Recitations Homework
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
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32. Resources Course Web Page Administrative handout Mailing Lists Forum
<
Administrative handout
Give you all of these details
Mailing Lists
Forum
Computer Accounts
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33. Pragmatics Programming in C and Assembly Online submission systems
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
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34. Feedback Sheets Please fill one out each class New course anonymous
Need to understand what works
So can improve for future lectures
So can improve for future years
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35. 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
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36. 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
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37. Questions
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