The Pervasive Computer

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INTRODUCTION

• The Pervasive Computer
• Computer are Everywhere
• They are capable of doing things for us
• Some Examples of What they do
• email, bank accounts,
• And (briefly) How they do it
• both simple and complex
• both similar and different

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Example-1 Email (electronic mail)

• Scenario
• Professor Newton (newton_at_cs.mit.edu) at MIT
  wants to send email to me (leonghw_at_comp.nus.edu.sg
  ).
• Simple
• Prof Newtons computer takes a string of
  characters and passes on to my computer.
• Complicated
• How does Prof Newtons computer know what to do
  with the string of letters?
• What does address leonghw_at_comp.nus.edu.sg mean?
• Where is that?

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Example-1 Email

• First, Text Processing.
• detect address to send to,
• detect which is the message part, and so on, etc
• Server/Router
• address ending with .sg
• send to a some gateway computer,
• which in turn will send it to a computer in
  Singapore.
• This computer in Singapore
• comp.nus.edu.sg --gt send to a computer in SoC.
• The computer in School of Computing
• stores it away in a mail file.
• When I log in and execute my mail reader, it
  shows me all the messages filed in the mail file.
  
• I can then ask it to show me the mail from Prof
  Newton.

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Example-1 Email

• So, what makes it work?
• To 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?
• Huge Volume -- Things become complex because we
  need to do this for hundreds of millions of
  users, sending and receiving tons of mail.
• Communication lines, networks may fail, etc.

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Example-2 Bank Account

• Scenario Maintaining Bank Accounts
• Isnt it simple?
• Depositing money is just addition, and
  withdrawing is just subtraction.
• Issues and Complications
• Thousands of customers, at hundreds of branches.
• To do the crediting to the correct account.
• Simultaneous access.
• Information needs to travel from the ATM machine
  to the computer, and back.

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Example-2 Bank Account

• Similar to Email in some ways.
• Needs processing, network of computer,
• so, we can use lots of similar hardware and
  software.
• But, also Different
• We need different kind of buttons on the ATM
  machine,
• We need to do printing on a different kind of
  paper,
• We need to read the ATM card, count money etc.

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More Examples

• LINC (library system), Online Registration
• Computer, hardware may be same.
• Different interface, Different software.
• Have a database of items (books), can search,
  reserve,
• MP3 music player
• Similar to LINC database
• You may search, access information in similar
  way.
• Difference
• now your machine interprets the information
  differently.
• It converts the message into sound a different
  interface.

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More Examples

• Scenario 3D Walkthrough in Video Games
• Question is it similar to what we have seen so
  far?
• 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.
• The software receives your position, and
  appropriately updates the 2D picture on your
  screen.
• Similar to how your ATM showed a different
  picture based on which account you are accessing
  or what operation you did.
• The calculations for 3D walkthrough are very
  complicated, but still similarities are there
  with other applications.

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Intelligent Computer

• Can do Email, library search, etc.
• store large amount of information
• find a particular piece of wanted information
• move the information quickly
• produce new information from old information
  quickly
• the changes need to be specified in a step by
  step manner ? Algorithm.
• the variety of algorithms that we can come up
  with is where the versatility of computers come
  from.

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Intelligent Computer (cont)

• Specifying an algorithm
• is however not simple, tedious, error prone,
• Requires professional training.
• You are able to use the computer because
• professionals have already done to hard work to
  make it look simple from your end.
• Complex
• Applications such as Word Processing, Email, etc
  require thousands or millions of lines of code.
• Easy to make errors. (example Y2K issue)

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Problem Adding 1 to 100

• Problem 123.99100
• Many Ways
• 123 336 6410
• 1234515 67891040
• Gausss Method
• 1100101 299101

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Algorithm Find sum from 1 to 100

• sum 0
• i 1
• repeat add i to sum
• add 1 to i
• i gt 100 ?
• no -gt repeat
• yes -gt finish

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Intelligent Computer (continued)

• That algorithm was simple!
• So how are we able to use computers for solving
  complicated problems?
• Two KEY IDEAS
• FIrst Generalize
• Second Combine different programs

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First Trick Generalize

• Generalized Problem find sum of n to m
• algorithm is very similar to old one
• sum 0
• i n
• repeat add i to sum
• add 1 to i
• i gt m ?
• no -gt repeat
• yes -gt finish
• HW Algorithm for
• find sum of n to m in steps of s?

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Combining Algorithms (programs)

• Decompose problem into smaller parts
• We can combine programs by
• using later programs to work on results of
  earlier programs.
• If we can divide into simple enough parts,
• then each part can be done separately, and then
  combined to give us the final product.

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However.

• We are not THERE yet,
• We still do not have working algorithms for all
  problems you may want to solve.
• Even not for some simple problems.
• Face recognition.
• Difficulty What exactly are we recognizing that
  is same in the photographs/persons?
• In Contrast, some problems are simpler.
• Finding the book by particular author in the huge
  number of books in the library is trivial for the
  computer.

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Intelligent Computer

• Common Capabilities
• User Interface
• the face of the computer
• Database
• Information store
• Different types of info
• Database Retrieval
• Fast, diverse
• Data Transmission
• Fast, accurate, secure
• Complex Data Processing

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Intelligent Computer What Intelligence?

• Human Intelligence
• Programmed into the computer
• Machine Intelligence
• Key Ideas
• Abstraction
• Knowledge Engineering

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What is Computer Science?

• Computer Science is NOT just
• the study of computers
• the study of how to write computer programs
• the study of the uses and applications of
  computers and software
• Computer Science is the study of algorithms,
  including
• their formal and mathematical properties,
• their hardware realizations,
• their linguistic realizations,
• their applications

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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.

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What is Computer Science?

• Can also define using the sub-areas
• Areas
• Algorithms and Data Structures
• Programming Languages
• Compilers and User Environments
• Software Engineering
• Computer Architecture
• Logic Design
• Computer Networking
• Artificial Intelligence
• Operating Systems
• Parallel Processing
• and many, many more

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History of Computers

• Processor (devices) Trends
• Technology Trends

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Processor Trends

• Intel 4004
• Intel 8008
• Pentium (80x86 series)
• Apple II
• IBM PC
• Non IBM PC (compatibles)

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Technology Trends

• User Interfaces
• Client Server Systems
• Formatting versus Processing
• Active Data
• Web Computer
• Web Business
• Mobile Computers

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THE END
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Intelligent Computer (cont)

• Computer (whats in it)
• Memory Box Which can identify contents by name
  (address)
• Arithmetic Unit Make calculations
• Pull data from memory, send to arithmetic unit,
  put back the answers to memory, etc.
• Know when to do what.
• Sort of pressing buttons on the calculator.
• You have to specify the algorithm in the
  particular language understood by the computer.
• Programming --gt algorithmlanguage

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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 gt m ?
• no -gt repeat
• yes -gt finish