Slide 1Why This Isn’t a Research Pitch1001 Questions0. What is Computer Science?Slide 5Slide 6What is the difference between Euclid and Ada?Geometry vs. Computer ScienceComputer Science1. What problem did the first electronic programmable computer solve?Colossus First Programmable ComputerColossus’ ProblemWhy perfectly secure?Breaking LorenzColossus2. Why was the first personal computer built?Apollo Guidance Computer, 1961-69AGC History3. Science, Engineering or Other?Science?Engineering?Computing Power 1969-2002 (in Apollo Control Computer Units)Constraints Computer Scientists FaceSo, what is computer science?The Liberal ArtsLiberal Arts4. What are the world’s most complex programs?Complex ProgramsHuman GenomeHow Big is the Make-a-Human Program?Encoding is RedundantExpressiveness of DNA5. How do Computer Scientists manage complexity?AbstractionAbstraction in Computer Science6. Who was the first Object-Oriented Programmer?What is an Object?Bjarne Stroustrup’s AnswerSlide 39Slide 40Who was the first object-oriented programmer?Slide 427. Who Invented the Internet?What is a Network?Chappe’s Semaphore NetworkinternetworkThe First InternetworkFirst Use of The InternetLicklider and Taylor’s VisionThe Modern Internet9. Why should we say “goodbye” to “Hello World!”?A C++ ProgramGoodbye “Hello World”Components of a C++ ProgramSummaryAny Questions?David [email protected]://www.cs.virginia.edu/evans/cs3901001 Things Every Self-Respecting Computer Scientist Should Know2Ethics andbut might not learn in CS101-CS3902 April 2003 1001 Things 2Why This Isn’t a Research Pitch•The students I want to work with are:–Resourceful enough to learn about my research by visiting my web page and reading papers–Smart enough to pick a thesis advisor by talking to current/recent students•I only have one hour and there are more important things to tell you than about my own research–I may go over, feel free to leave at any time2 April 2003 1001 Things 31001 Questions0000 What is Computer Science?0001 What problem did the first electronic programmable computer solve?0010 Why was the first “personal computer” built?0011 Is Computer Science a science, engineering or other?0100 What are the world’s most complex programs?0101 How do Computer Scientists manage complexity?0110 Who was the first object-oriented programmer?0111 Who invented the Internet?1000 Why should we say goodbye to “Hello World!”?2 April 2003 1001 Things 40. What is Computer Science?2 April 2003 1001 Things 5Let AB and CD be the two given numbers not relatively prime. It is required to find the greatest common measure of AB and CD.If now CD measures AB, since it also measures itself, then CD is a common measure of CD and AB. And it is manifest that it is also the greatest, for no greater number than CD measures CD. Euclid’s Elements, Book VII, Proposition 2 (300BC)2 April 2003 1001 Things 6The note on the inflected line is only difficult to you, because it is so easy. There is in fact nothing in it, but you think there must be some grand mystery hidden under that word inflected! Whenever from any point without a given line, you draw a long to any point in the given line, you have inflected a line upon a given line.Ada Byron (age 19), letter to Annabella Acheson (explaining Euclid), 18342 April 2003 1001 Things 7What is the difference between Euclid and Ada?“It depends on what your definition of ‘is’ is.” Bill Gates (at Microsoft’s anti- trust trial)2 April 2003 1001 Things 8Geometry vs. Computer Science•Geometry (mathematics) is about declarative knowledge: “what is” If now CD measures AB, since it also measures itself, then CD is a common measure of CD and AB•Computer Science is about imperative knowledge: “how to”–About “computing” not “computers”–An unnatural science2 April 2003 1001 Things 9Computer Science“How to” knowledge:•Ways of describing imperative processes (computations)•Ways of reasoning about (predicting) what imperative processes will doLanguageLogic2 April 2003 1001 Things 101. What problem did the first electronic programmable computer solve?2 April 2003 1001 Things 11ColossusFirst Programmable Computer•Bletchley Park, 1943•Designed by Tommy Flowers•10 Colossi in operation at end of WWII•Destroyed in 1960, kept secret until 1970s•(2 years before ENIAC – calculating artillery tables)2 April 2003 1001 Things 12Colossus’ Problem•Decode Nazi high command messages from Lorenz Machine •XOR encoding:Ci = Mi Ki–Perfect cipher, if K is random and secret2 April 2003 1001 Things 13For any given ciphertext, all plaintexts are equally possible.Ciphertext: 0100111110101Key: 1100000100110Plaintext: 1000111010011 = “CS”Why perfectly secure?10B2 April 2003 1001 Things 14Breaking Lorenz•Operator and receiver need same keys•Generate key bits using rotor machine, start with same configuration•One operator retransmitted a message (but abbreviated message header the second time!)•Enough for Bletchley Park to figure out key – and structure of machine that generated it!•But still had to try all configurations2 April 2003 1001 Things 15Colossus•Read ciphertext and Lorenz wheel patterns from tapes•Tried each alignment, calculated correlation with German•Decoded messages (63M letters by 10 Colossus machines) that enabled Allies to know German troop locations to plan D-Day2 April 2003 1001 Things 162. Why was the first personal computer built?2 April 2003 1001 Things 17Apollo Guidance Computer, 1961-691 cubic foot, 70 poundsWhy did they need to fit the guidance computer in the rocket?4KB of read/write magnetic core memory64KB of read-only memory2 April 2003 1001 Things 18AGC History•Needed all guidance to be on board in case Soviets jammed signals for Earth•Design began in 1961•Risky decision to use Integrated Circuits (invented in 1958)–Building 4 prototypes used 60% of all ICs produced in the US in the early 60s!–Spurred industry growth2 April 2003 1001 Things 193. Science, Engineering or Other?2 April 2003 1001 Things 20Science?•Understanding Nature through Observation–About real things like bowling balls, black holes, antimatter, electrons, comets, etc.•Math and Computer Science are about fake things like numbers, graphs, functions, lists, etc.–Computer Science is a useful tool for doing real science, but not a real science2 April 2003 1001 Things
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