1. LeongHW, SoC, NUS (UTT2201: Introduction) Page 1 INTRODUCTION  The Pervasive Computer o Computer are Everywhere o They are capable of doing things for us  Some Examples of What they do o email, bank accounts,  And (briefly) How they do it o both simple and complex o both similar and different

2. LeongHW, SoC, NUS (UTT2201: Introduction) Page 2 Example-1: Email (electronic mail) Scenario: Professor Newton (newton@cs.mit.edu) at MIT wants to send email to me (leonghw@comp.nus.edu.sg).newton@cs.mit.edu  Simple: oProf Newton’s computer takes a string of characters and passes on to my computer.  Complicated: oHow does Prof Newton’s computer know what to do with the string of letters? oWhat does address leonghw@comp.nus.edu.sg mean? oWhere is that?

3. LeongHW, SoC, NUS (UTT2201: Introduction) Page 3 Example-1: Email  First, Text Processing. odetect address to send to, odetect which is the message part, and so on, etc  Server/Router: oaddress ending with “.sg” osend to a some gateway computer, owhich in turn will send it to a computer in Singapore.  This computer in Singapore ocomp.nus.edu.sg --> send to a computer in SoC.  The computer in School of Computing ostores it away in a mail file. oWhen I log in and execute my mail reader, it shows me all the messages filed in the mail file. oI can then ask it to show me the mail from Prof Newton.

4. LeongHW, SoC, NUS (UTT2201: Introduction) Page 4 Example-1: Email  So, what makes it work? oTo do all this work we need  various machines to be linked together -- network using communication lines – the engineering folks.  Machines need to know what to do with individual messages, detect the addresses, sender, message content etc.  Why is it Complicated? oHuge Volume -- Things become complex because we need to do this for hundreds of millions of users, sending and receiving tons of mail. oCommunication lines, networks may fail, etc.

5. LeongHW, SoC, NUS (UTT2201: Introduction) Page 5 Example-2: Bank Account Scenario: Maintaining Bank Accounts  Isn’t it simple? oDepositing money is just addition, and withdrawing is just subtraction.  Issues and Complications oThousands of customers, at hundreds of branches. oTo do the crediting to the correct account. oSimultaneous access. oInformation needs to travel from the ATM machine to the computer, and back.

6. LeongHW, SoC, NUS (UTT2201: Introduction) Page 6 Example-2: Bank Account  Similar to Email in some ways. oNeeds processing, network of computer, oso, we can use lots of similar hardware and software.  But, also Different: oWe need different kind of buttons on the ATM machine, oWe need to do printing on a different kind of paper, oWe need to read the ATM card, count money etc.

7. LeongHW, SoC, NUS (UTT2201: Introduction) Page 7  LINC (library system), Online Registration oComputer, hardware may be same. oDifferent interface, Different software. oHave a database of items (books), can search, reserve,  MP3 music player oSimilar to LINC database  You may search, access information in similar way. oDifference  now your machine interprets the information differently.  It converts the message into sound: a different interface. More Examples:

8. LeongHW, SoC, NUS (UTT2201: Introduction) Page 8 Scenario: 3D Walkthrough in Video Games  Question: is it similar to what we have seen so far? o The computer has a big file describing the 3D structure, and can work out mathematically what it would look like in 2D from a particular angle. oThe software receives your position, and appropriately updates the 2D picture on your screen. oSimilar to how your ATM showed a different picture based on which account you are accessing or what operation you did. oThe calculations for 3D walkthrough are very complicated, but still similarities are there with other applications. More Examples:

9. LeongHW, SoC, NUS (UTT2201: Introduction) Page 9 Intelligent Computer  Can do Email, library search, etc. o store large amount of information o find a particular piece of wanted information o move the information quickly o produce new information from old information quickly o the changes need to be specified in a step by step manner  Algorithm. o the variety of algorithms that we can come up with is where the versatility of computers come from.

10. LeongHW, SoC, NUS (UTT2201: Introduction) Page 10 Intelligent Computer (cont…)  Specifying an algorithm ois however not simple, tedious, error prone, o Requires professional training.  You are able to use the computer because oprofessionals have already done to hard work to make it look simple from your end.  Complex: oApplications such as Word Processing, Email, etc require thousands or millions of lines of code. oEasy to make errors. (example: Y2K issue)

11. LeongHW, SoC, NUS (UTT2201: Introduction) Page 11 Problem: Adding 1 to 100  Problem: 1+2+3….+99+100  Many Ways: o1+2=3; 3+3=6; 6+4=10; … … o1+2+3+4+5=15; 6+7+8+9+10=40; …  Gauss’s Method: o1+100=101; 2+99=101; …

12. LeongHW, SoC, NUS (UTT2201: Introduction) Page 12 Algorithm: Find sum from 1 to 100 sum = 0 i = 1 repeat: add i to sum add 1 to i i > 100 ? no -> repeat yes -> finish

13. LeongHW, SoC, NUS (UTT2201: Introduction) Page 13 Intelligent Computer (continued)  That algorithm was simple!  So how are we able to use computers for solving complicated problems?  Two KEY IDEAS: oFIrst: Generalize oSecond: Combine different programs

14. LeongHW, SoC, NUS (UTT2201: Introduction) Page 14 First Trick: Generalize  Generalized Problem: find sum of n to m oalgorithm is very similar to old one… sum = 0 i = n repeat: add i to sum add 1 to i i > m ? no -> repeat yes -> finish  HW: Algorithm for o find sum of n to m in steps of s?

15. LeongHW, SoC, NUS (UTT2201: Introduction) Page 15 Combining Algorithms (programs)  Decompose problem into smaller parts: oWe can combine programs by  using later programs to work on results of earlier programs.  If we can divide into simple enough parts, othen each part can be done separately, and then combined to give us the final product.

16. LeongHW, SoC, NUS (UTT2201: Introduction) Page 16  We are not THERE yet, oWe still do not have working algorithms for all problems you may want to solve.  Even not for some “simple” problems. oFace recognition.  Difficulty: What exactly are we recognizing that is same in the photographs/persons?  In Contrast, some problems are simpler. oFinding the book by particular author in the huge number of books in the library is trivial for the computer. However….

17. LeongHW, SoC, NUS (UTT2201: Introduction) Page 17 Intelligent Computer  Common Capabilities o User Interface  “the face” of the computer o Database  Information store  Different types of info… o Database Retrieval  Fast, diverse o Data Transmission  Fast, accurate, secure o Complex Data Processing

18. LeongHW, SoC, NUS (UTT2201: Introduction) Page 18 Intelligent Computer – What Intelligence?  Human Intelligence  “Programmed” into the computer  Machine Intelligence  Key Ideas: oAbstraction oKnowledge Engineering

19. LeongHW, SoC, NUS (UTT2201: Introduction) Page 19 What is Computer Science?  Computer Science is NOT just o the study of computers o the study of how to write computer programs o the study of the uses and applications of computers and software  Computer Science is the study of algorithms, including o their formal and mathematical properties, o their hardware realizations, o their linguistic realizations, o their applications

20. LeongHW, SoC, NUS (UTT2201: Introduction) Page 20 Algorithm al go rithm n. A procedure for solving a mathematical problem in a finite number of steps that frequently involves repetition of an operation; broadly: a step-by-step method for accomplishing some task.  Informally: an algorithm is an ordered sequence of instructions that is guaranteed to solve a specific problem.  Example of an algorithm: Step 1: Wet your hair Step 2: Lather your hair Step 3: Rinse your hair Step 4:Lather your hair Step 5:Rinse your hair Step 6:Stop.

21. LeongHW, SoC, NUS (UTT2201: Introduction) Page 21 What is Computer Science?  Can also define using the sub-areas:  Areas: o Algorithms and Data Structures o Programming Languages o Compilers and User Environments o Software Engineering o Computer Architecture o Logic Design o Computer Networking o Artificial Intelligence o Operating Systems o Parallel Processing o and many, many more…

22. LeongHW, SoC, NUS (UTT2201: Introduction) Page 22 History of Computers…  Processor (devices) Trends  Technology Trends

23. LeongHW, SoC, NUS (UTT2201: Introduction) Page 23 Processor Trends  Intel 4004  Intel 8008  Pentium (80x86 series)  Apple II  IBM PC  Non IBM PC (compatibles)

24. LeongHW, SoC, NUS (UTT2201: Introduction) Page 24 Technology Trends…  User Interfaces  Client Server Systems  Formatting versus Processing  Active Data  Web Computer  Web Business  Mobile Computers

25. LeongHW, SoC, NUS (UTT2201: Introduction) Page 25 THE END

26. LeongHW, SoC, NUS (UTT2201: Introduction) Page 26

27. LeongHW, SoC, NUS (UTT2201: Introduction) Page 27  Computer (what’s in it): oMemory Box: Which can identify contents by name (address) oArithmetic Unit: Make calculations oPull data from memory, send to arithmetic unit, put back the answers to memory, etc.  Know when to do what. oSort of pressing buttons on the calculator. oYou have to specify the algorithm in the particular language understood by the computer. oProgramming --> algorithm+language Intelligent Computer (cont…)

28. LeongHW, SoC, NUS (UTT2201: Introduction) Page 28 Intelligent Computer (more…)  Generalize: Find sum of n to m in steps of s sum = 0 i = n repeat: add i to sum add s to i i > m ? no -> repeat yes -> finish