CMSC 120: Visualizing Information

1
Introduction to Computing

• CMSC 120 Visualizing Information
• 1/29/08

2
What is Computing?

• To determine by calculating
• To use a computer

What is a Computer?

• A device that accepts information (data),
• processes it according to specific instructions,
• and provides the results as new information

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First Computers
A computer a person who works with numbers
Pen and Paper
People
0 1 2 3 4 5 6 7 8 9
Number Systems
Abacus
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Mechanical Age (1450-1840)
Slide Rule

• Early 1600s
• An analog computer

Pascaline

• Blaise Pascal (1642)
• A gear driven adding machine

Analog represents data by measurement of a
continuous physical variable
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Mechanical Age (1450-1840)
Stepped Reckoner

• Gottfried Wilhelm von Leibniz (1670s)
• Add, subtract, multiply, divide
• Mechanically unreliable

6
Mechanical Age (1450-1840)
Punch Card

• Joseph Jacquard (1810)
• Weaving instructions for looms stored in cards
  with holes punched in them

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Mechanical Age (1450-1840)
The Analytical Engine

• Followed program in punched cards
• Store information in memory unit
• Make decisions

The Difference Engine (1822)

• Charles Babbage

8
Analytical Engine Anecdote

• Babbages collaborator was Ada, Countess of
  Lovelace, daughter of Lord Bryon
• Sponsored, tested, publicized device
• First Programmer
• Stated that the engine would never originate
  anything
• A machine, no matter how powerful, could think

9
Electro-mechanical Age (1840 1940)

• Hermann Hollerith (end 19th century)
• Created to tabulate US Census
• Used electricity
• Information punched into cards
• Metal pins open and closed electrical circuits

Electronic Tabulating Machine

• Population 63 million 6 weeks
• Founding product of International Business
  Machines (IBM)

10
Electro-mechanical Age (1840 1940)

• IBM Harvard under leadership of Howard Aiken
  (1930s)
• Storage Mechanical relay telephone switches
• Input Punch Cards
• Output
• No decision making

51 feet in length 5 tons 750, 000 parts
Mark I
What is the difference between a calculator and a
computer?
11
The First Computer Bug

• Grace Hopper (1909 1992)
• One of first programmers of Mark I
• Developed first compiler

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Electronic Age (1840 Today)
Electronic Numerical Integration and Calculator
(ENIAC)

• John Mauchly and J. Presper Eckert (finished
  1946)
• Initially secret military project begun during
  WWII
• University of Pennsylvania

13
Electronic Age (1840 Today)

• Occupied 1500 square feet
• Weighed 30 tons
• Used vacuum tubes
• gt17,000
• Able to make decisions first true computer
• Programming involved wiring and switch flipping

ENIAC
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Electronic Age (1840 Today)

• John von Neumann (1940s)
• Storing computer instructions in a central
  processing unit (CPU)
• No longer necessary to flip switches or rewire
• Large Corporations, US Government

Stored Program Computer

• Processing Model
• Input data
• Store data while being processed
• Process data according to specific instructions
• Output the results in the form of new data

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Electronic Innovations

• Vacuum tubes
• Large and expensive
• UNIVAC 35 tons
• 1000 calculations per second
• Transistor semiconductor used as an amplifier or
  electronically controlled switch
• Reduced size
• 10,000 claculations per second
• IBM model 650 (1960s)
• Magnetic tape replaced punched cards

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Electronic Innovations

• Integrated Circuits
• Replacement of transistors with integrated
  circuits or chips
• Silicon blocks with logic circuits etched onto
  surface
• Millions of calculations per second
• IBM System 360 was one of the first computers to
  use integrative circuits
• Hospitals and Universities could now own
  computers

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Modern Computers

• 1951 1958 Vacuum tubes (First Generation)
• 1959 1964 Transistors (Second Gen)
• 1965 1970 Integrated Circuits (Third Gen)
• 1970 Large Scale Chips and Microprocessors
  (Fourth Gen)

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Modern Computers

• Microprocessor a CPU an a single chip
• Designed in 1970 by Marcian Hoff (Intel
  Corporation)
• Microcomputer a desktop size computer
• ALTAIR (1975)
• Apple (Stephen Wozniak and Steven Jobs 1977)

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The State of Modern Computing

• Computing power doubles every 18-24 months

From the BBC
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Hardware (Computer Architecture)

• Input Devices
• Memory
• Central Processing Unit
• Output Devices

Input
Memory
Output
CPU
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Memory

• Read Only Memory (ROM)
• Most basic operating instructions
• Permanent
• Random Access Memory (RAM)
• Main memory
• Data and instructions are temporarily stored
• Registers
• Temporary memory locations within the CPU
• Auxiliary Memory

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CPU

• Directs all activities of the computer
• All information flows through the CPU
• Brain
• Only executes tasks according to instructions it
  has been given
• Arithmetic Logic Unit (ALU)
• Adds
• Compares

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Software

• Computer programs
• Interface between computer and user
• Disk Operating System (DOS)
• MS-DOS, Windows, Linux, UNIX
• Graphical User Interface (GUI)