CMSC 120: Visualizing CMSC 120: Visualizing InformationInformation

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Introduction to Introduction to ComputingComputing

What is Computing?What is Computing?

To determine by calculatingTo determine by calculating To use a computerTo use a computer

What is a Computer?What is a Computer?

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

First ComputersFirst Computers

Abacus

0 1 2 3 45 6 7 8 9 Number Systems

Pen and Paper

People

*A computer: a person who works with numbers

Mechanical Age (1450-Mechanical Age (1450-1840)1840)

Pascaline Blaise Pascal (1642)Blaise Pascal (1642) A gear driven adding A gear driven adding

machinemachine

Slide Rule

Early 1600sEarly 1600s An analog computerAn analog computer

Analog: represents data by measurement ofa continuous physical variable

Mechanical Age (1450-Mechanical Age (1450-1840)1840)

Gottfried Wilhelm Gottfried Wilhelm von Leibniz von Leibniz (1670s)(1670s)

Add, subtract, Add, subtract, multiply, dividemultiply, divide

Mechanically Mechanically unreliableunreliable

Stepped Reckoner

Mechanical Age (1450-Mechanical Age (1450-1840)1840)

Punch Card Joseph Jacquard (1810)Joseph Jacquard (1810) Weaving instructions for looms stored in cards Weaving instructions for looms stored in cards

with holes punched in themwith holes punched in them

Mechanical Age (1450-Mechanical Age (1450-1840)1840)

The Difference Engine (1822)

The Analytical Engine

Charles Charles BabbageBabbage

Followed program in punched Followed program in punched cardscards

Store information in memory Store information in memory unitunit

Make decisionsMake decisions

Analytical Engine AnecdoteAnalytical Engine Anecdote

Babbage’s collaborator was Ada, Countess Babbage’s collaborator was Ada, Countess of Lovelace, daughter of Lord Bryonof Lovelace, daughter of Lord Bryon

Sponsored, tested, publicized deviceSponsored, tested, publicized device

““First Programmer”First Programmer”

Stated that the engine would never Stated that the engine would never “originate anything”“originate anything”– A machine, no matter how powerful, could thinkA machine, no matter how powerful, could think

Electro-mechanical Age (1840 – Electro-mechanical Age (1840 – 1940)1940)

Hermann Hollerith (end Hermann Hollerith (end 1919thth century) century)

Created to tabulate US Created to tabulate US CensusCensus

Used electricityUsed electricity

Information punched Information punched into cardsinto cards

Metal pins open and Metal pins open and closed electrical closed electrical circuitscircuits

Electronic Tabulating Machine Population: 63 million; 6 weeksPopulation: 63 million; 6 weeks Founding product of Founding product of

International Business International Business Machines (IBM)Machines (IBM)

Electro-mechanical Age (1840 – Electro-mechanical Age (1840 – 1940)1940)

IBM + Harvard IBM + Harvard under leadership of under leadership of Howard Aiken Howard Aiken (1930s)(1930s)

Storage: Mechanical Storage: Mechanical relay telephone relay telephone switchesswitches

Input: Punch CardsInput: Punch Cards

OutputOutput

No decision makingNo decision making

Mark I

51 feet in length5 tons

750, 000 parts

What is the difference between a calculator and a computer?

The First Computer BugThe First Computer Bug

Grace Hopper (1909 – Grace Hopper (1909 – 1992)1992)

One of first One of first programmers of Mark Iprogrammers of Mark I

Developed first Developed first compilercompiler

Electronic Age (1840 – Today)Electronic Age (1840 – Today)

Electronic Numerical Integration and Calculator (ENIAC)

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

Electronic Age (1840 – Electronic Age (1840 – Today)Today)

Occupied 1500 square feetOccupied 1500 square feet

Weighed 30 tonsWeighed 30 tons

Used vacuum tubesUsed vacuum tubes– >17,000>17,000

Able to make decisions: Able to make decisions: first true computerfirst true computer

Programming involved Programming involved wiring and switch flippingwiring and switch flipping

ENIAC

Electronic Age (1840 – Electronic Age (1840 – Today)Today)

John von Neumann John von Neumann (1940s)(1940s)

Storing computer Storing computer instructions in a instructions in a central processing unitcentral processing unit (CPU)(CPU)– No longer necessary to No longer necessary to

flip switches or rewireflip switches or rewire

Large Corporations, Large Corporations, US GovernmentUS Government

Stored Program Computer

Processing Model:Processing Model:– Input dataInput data– Store data while being processedStore data while being processed– Process data according to specific Process data according to specific

instructionsinstructions– Output the results in the form of new dataOutput the results in the form of new data

Electronic InnovationsElectronic Innovations

Vacuum tubesVacuum tubes– Large and expensiveLarge and expensive– UNIVAC: 35 tonsUNIVAC: 35 tons– 1000 calculations per second1000 calculations per second

Transistor: semiconductor used as an amplifier or Transistor: semiconductor used as an amplifier or electronically controlled switchelectronically controlled switch– Reduced sizeReduced size– 10,000 claculations per second10,000 claculations per second– IBM model 650 (1960s)IBM model 650 (1960s)– Magnetic tape replaced punched cardsMagnetic tape replaced punched cards

Electronic InnovationsElectronic Innovations

Integrated CircuitsIntegrated Circuits– Replacement of transistors with integrated circuits or Replacement of transistors with integrated circuits or

chipschips– Silicon blocks with logic circuits etched onto surfaceSilicon blocks with logic circuits etched onto surface– Millions of calculations per secondMillions of calculations per second

– IBM System 360 was one of the first computers to use IBM System 360 was one of the first computers to use integrative circuitsintegrative circuits

– Hospitals and Universities could now own computersHospitals and Universities could now own computers

Modern ComputersModern Computers

1951 – 1958: Vacuum tubes (First 1951 – 1958: Vacuum tubes (First Generation)Generation)

1959 – 1964: Transistors (Second Gen)1959 – 1964: Transistors (Second Gen)

1965 – 1970: Integrated Circuits (Third Gen)1965 – 1970: Integrated Circuits (Third Gen)

1970 + : Large Scale Chips and 1970 + : Large Scale Chips and Microprocessors (Fourth Gen)Microprocessors (Fourth Gen)

Modern ComputersModern Computers

MicroprocessorMicroprocessor: a CPU an a single chip: a CPU an a single chip– Designed in 1970 by Marcian Hoff (Intel Designed in 1970 by Marcian Hoff (Intel

Corporation)Corporation)

MicrocomputerMicrocomputer: a desktop size computer: a desktop size computer– ALTAIR (1975)ALTAIR (1975)– Apple (Stephen Wozniak and Steven Jobs; 1977)Apple (Stephen Wozniak and Steven Jobs; 1977)

The State of Modern The State of Modern ComputingComputing

Computing power Computing power doubles every 18-doubles every 18-24 months24 months

From the BBC

Hardware Hardware (Computer Architecture)(Computer Architecture)

Input DevicesInput Devices MemoryMemory Central Processing UnitCentral Processing Unit Output DevicesOutput Devices

Input Memory Output

CPU

MemoryMemory Read Only Memory (ROM)Read Only Memory (ROM)

– Most basic operating instructionsMost basic operating instructions– PermanentPermanent

Random Access Memory (RAM)Random Access Memory (RAM)– Main memoryMain memory– Data and instructions are temporarily storedData and instructions are temporarily stored

RegistersRegisters– Temporary memory locations within the CPUTemporary memory locations within the CPU

Auxiliary MemoryAuxiliary Memory

CPUCPU

Directs all activities of the computerDirects all activities of the computer All information flows through the CPUAll information flows through the CPU ““Brain”Brain”

– Only executes tasks according to Only executes tasks according to instructions it has been giveninstructions it has been given

Arithmetic Logic Unit (ALU)Arithmetic Logic Unit (ALU)– AddsAdds– ComparesCompares

SoftwareSoftware

Computer programsComputer programs

Interface between computer and Interface between computer and useruser– Disk Disk Operating System Operating System (DOS)(DOS)– MS-DOS, Windows, Linux, UNIXMS-DOS, Windows, Linux, UNIX

Graphical User Interface (GUI)Graphical User Interface (GUI)