CSCI N201

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• CSCI N201
• Programming Concepts and Database
• 3 Essence of Computing
• Lingma Acheson
• linglu_at_iupui.edu

Department of Computer and Information Science,
IUPUI
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Definition of Computer

• Universal
• Information
• Manipulator

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Definition of Computer

• Universal
• Works with all kinds of information
• Words, maths, images, videos
• Performs different tasks
• Games, create a document read books, long
  distance calls, modify images
• Very few limitations
• Do anything with any kind of information

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Definition of Computer

• Information
• Seems to be able to work with anything
• Actually very limited
• All translated into 1s and 0s
• Tiny pieces of data combined into complex
  information

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Definition of Computer

• Manipulator
• Seem able to do anything with data
• Actually very limited
• Come down to a few basic operations
• Simple commands combined into complex instructions

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Computer and Information

• Information limited to on/off impulses, like a
  light switch
• Light switch demo
• http//wally.cs.iupui.edu/n100/update/binLights.ht
  ml
• One light switch
• 1 on, 0 off
• Two messages Have a lecture class today? (on
  yes off no)
• Two light switches
• Switch one Have a lecture class today? (on
  yes off no)
• Switch two Have a lab class today? (on yes
  off no)
• How many messages can two switches send?

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Computer and Information

• Three light switches
• Switch one Have a lecture class today? (on
  yes off no)
• Switch two Have a lab class today? (on yes
  off no)
• Switch three Have a quiz today? (on yes off
  no)
• How many messages can two switches send?
• Adding each extra switch will double the number
  of messages
• 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, .

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Computer and Information

• Related to how computers store information
• Brick counter demo
• http//wally.cs.iupui.edu/n100/update/legoMover.ht
  ml
• Represent 1, 2, 4, 8
• How to represent other numbers? (0 15)
• How to represent more numbers?

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Binary Conversion

• Converting from binary to base 10
• Use a spreadsheet
• E.g. 1 101
• Brick Demo

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Binary Conversion

• E.g. 2 1101
• E.g. 3 1010
• Try it yourself!

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Binary Conversion

• How are binary numbers related to base 10
  numbers?
• E.g., 367

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Binary Conversion

• Binary numbers, base 2. Able to deal with any
  number with the power of 2
• Binary 101 122 021 120 5
• Decimal 101 1102 0101 1100 101

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Binary Conversion

• Base 10, 0 9 digits, add more digits as numbers
  grow
• Base 2, 0 1, add more switches as numbers grow

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Binary Conversion

• Converting from base 10 to binary
• Use a spreadsheet
• Try it yourself!

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Binary Conversion

• Converting from base 10 to binary
• Large numbers
• E.g., 34
• What is the result from using spreadsheet?
• 34/2 17 with a remainder of 0
• 17/2 8 with a remainder of 1
• 8/2 4 with a remainder of 0
• 4/2 2 with a remainder of 0
• 2/2 1 with a remainder of 0
• 1/2 0 with a remainder of 1
• Result 100010 (get the remainder backwards)
• E.g. 157

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Computer Definition Revisit

• Information
• Only deal with 1s and 0s
• Binary conversion readings
• http//www.cs.iupui.edu/n241/readings/binconv.htm
  l

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Computer Definition Revisit

• Operation
• Very limited
• Only three logical operations
• AND, OR, NOT

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Basic Logic Gates

• True or False conditions
• E.g.I have a football. True, False?
• Why True or False ? 1 or 0
• Add logic operations
• E.g. I have a football and a baseball.
• I have a football or a baseball.
• I do not have a football.
• E.g. A hardware device example

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Basic Logic Gates

• Truth tables
• Logical AND

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Basic Logic Gates

• Truth tables
• Logical OR

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Basic Logic Gates

• Truth tables
• Logical NOT

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Basic Logic Gates

• These devices are called gates
• Turning them into electronic devices, we can put
  them together to build electronic circuit boards
  and components, and make computers do different
  jobs, such as adding or subtracting binary
  numbers
• Everything comes down to the operations of the
  three logic gates

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Basic Logic Gates

• Practice
• If you are a student of computer science, or if
  you are a freshman, you can access the computers
  in this lab.
• Can I access the computers in this lab if I am a
  first year computer science student?
• If ((midtermgt80) and (finalgt90)) then gradeA
• Will Sam get an A if his midterm score is 85
  and final is 89?
• If (count lt3) then let the user try again.
• Mary has tried logging to the account three
  times, will she be allowed to try again?
• If you are taller than 4ft, or you are over 16
  years old, then you can ride the roller coaster.
• Peter is 15 years old, can he ride the roller
  coaster?