1

COMS 161Introduction to Computing

Title: Computer Organization

Date: March 25, 2005

Lecture Number: 27

2

Announcements

• Research paper rough draft– Due Monday 3/28/2005

3

Review

• HTML– Document structure

• Tables

4

Outline

• Computer Systems– Mechanical computers

• Pascal• Babbage• Hollerith

– Mechanical and electrical

– Electromechanical• Harvard Mark I

– Electronic• ABC, ENIAC, EDVAC

5

Computer Systems

• A dime a dozen!!– They are everywhere and their uses

continue to expand• Microwaves• Clocks• Cars• Watches• What’s next

– Shoes??– My Drawers??

6

Computer System

• Electronic digital data processing machines– Data: symbolic representation of

information

– Digital: numeric codes

– Computers are discrete state machines• Finite number of states

– All are distinct and different

• Always in a state

7

Computer System

• Process– Set of actions

– Traversing certain states• Sequence of distinct states

– Fast to go from one state to another• Billionths of a second

– So fast, a process appears continuous• As do light bulbs• Your TV screen

8

Computer System

• Mechanical computers– Blaise Pascal (1623-1662)

– Develops a mechanism to calculate with 8 figures and carrying of 10's , 100's, and 1000's etc.

– Could add two decimal numbers

– Could also subtract using 10’s complement

– The machine is called the 'Pascaline'

9

Pascaline

10

Pascaline

11

Mechanical computers

• Charles Babbage (1791-1871)– Tables of logarithmic and trigonometric functions,

were generated by teams of mathematicians working day and night on primitive calculators

– Since people performed computations they were referred to as computers

– He proposed building a machine called the Difference Engine to automatically calculate these tables

12

Mechanical computers

• Charles Babbage (1791-1871)– The Difference Engine was partially completed

when Babbage conceived the idea of another, more sophisticated machine called an Analytical Engine

– The Analytical Engine was to use loops of punched cards to control an automatic calculator

– Decisions could be based on the results of previous computations

13

Mechanical computers

• Charles Babbage (1791-1871)– The Analytical Engine employed several features

found in modern computers• Sequential control• Branching• Looping

– He worked on the Analytical Engine from 1930 until he died

14

Mechanical computers

• Charles Babbage (1791-1871)– Ada Lovelace, the daughter of the English poet

Lord Byron wrote a program for the Analytical Engine

– Ada was a mathematician and fully understood Babbage's vision

– Ada’s program would have computed Bernoulli numbers

15

Mechanical computers

• Charles Babbage (1791-1871) – Often referred to as the "Father of Computing"

for his contributions to the development of the computer

– He produced a prototype of this "difference engine" by 1822

– It was intended to be steam-powered– Fully automatic, even to the printing of the

resulting tables– Commanded by a fixed instruction program

16

Difference and Analytical Engine

17

Mechanical Computers

• Herman Hollerith– Estimated that compiling the data for the 1890

census would take until after the 1900 census– Idea was to use punched cards to represent the

census data– The data could be read and collates using an

automatic machine– He built a mechanism that could read the

presence or absence of holes in the cards• Using spring-mounted nails that passed through the

holes to make electrical connections

18

Mechanical Computers

• Herman Hollerith– The system included an automatic electrical

tabulating machine with a large number of clock-like counters that accumulated results

– Widely regarded as the father of modern automatic computation

– He founded the company that was to become IBM

– Hollerith's designs dominated the computing landscape for almost 100 years

19

Hollerith 1890 Census Tabulator

20

Hollerith Punch Card

21

IBM Punch Card

22

Computer System

• Electromechanical computer– During the late 1930s punched-card machine

techniques had become so well established and reliable

– Howard Aiken, in collaboration with engineers at IBM, undertook construction of a large automatic digital computer based on standard IBM electromechanical parts

– Handled 23-decimal-place numbers

23

Computer System

• Electromechanical computer– IBM called the machine

• automatic sequence controlled calculator (ASCC)

– It is better known• Harvard Mark I,

24

Harvard Mark I

• 1944

• 51 feet long

• weighs 5 tons

• incorporates 750,000 parts

25

Harvard Mark I

26

Computer System

• Electronic Computer

– Fastest, but still performs simple steps

– One of the great illusion of the computer: • Lots of simple steps performed quickly enough

make the computer appear complicated

27

Computer System

• Electronic computer– John Vincent Atanasoff (1903 - 1995)– Clifford Berry (1918 - 1963)

• Built the world's first electronic-digital computer at Iowa State University between 1939 and 1942

• The Atanasoff-Berry Computer (ABC) represented several innovations in computing

– a binary system of arithmetic– parallel processing– regenerative memory– separation of memory and computing functions

28

Electronic Computer

• Atanasoff performed intensive computing while working on his doctorate in theoretical physics (late 1920’s – 1930)– The forgotten father of computing– Faculty member at Iowa State College in

mathematics and physics– In 1937 worked out the design– In 1939 he hired a student Clifford Berry to help

him construct the machine– By 1941 they had a working machine

29

Electronic Computer

• Clifford Berry with ABC in 1942

30

Electronic Computer

• Replica of ABC

31

Electronic Computer

• In 1946, John Eckert and John Mauchley built Electronic Integrator and Computer (ENIAC)– Specific task was compiling tables for the

trajectories of bombs and shells– It contained roughly 18,000 vacuum tubes– Measured about 2.5 meters in height and 24

meters in length– The machine was more than 1000 times faster

than its electromechanical predecessors– It could execute up to 5000 additions per second

32

Electronic Computer

• ENIAC– The first general purpose computer

33

Electronic Computer

– The ENIAC machine occupied a room thirty by fifty feet

– The controls are at the left– A small part of the output device is at the right

34

Electronic Computer

35

Electronic Computer

• Improvement ideas developed as ENIAC was built– The stored program concept among them

• John von Neumann

– EDVAC• A new machine with improvements over

ENIAC• The first stored program computer

36

Enter the Sharks

• Mauchley filed and received patents for the first general computer

• However– Mauchly visited Atanasoff in 1941 and was

inspired by Atanasoff's work– In 1941 Atanasoff knew more about basic

elements of electronic computation than Mauchly and openly shared this knowledge

– Enter the lawyers• Early 1967

37

Sharks

• October 19, 1973– Judge Larson had ruled that John Vincent

Atanasoff and Clifford Berry had constructed the first electronic digital computer at Iowa State College in the 1939 - 1942 period

– He had also ruled that Mauchly and Eckert, who had for more than twenty-five years been feted, trumpeted, and honored as the co-inventors of the first electronic digital computer, were not entitled to the patent upon which that honor was based

38

Sharks

• October 19, 1973– Judge Larson had ruled that John Vincent

Atanasoff and Clifford Berry had constructed the first electronic digital computer at Iowa State College in the 1939 - 1942 period

– He had also ruled that Mauchly and Eckert, who had for more than twenty-five years been feted, trumpeted, and honored as the co-inventors of the first electronic digital computer

• Were not entitled to the patent upon which that honor was based

39

Sharks

• October 19, 1973– Judge Larson also ruled

• Mauchly had pirated Atanasoff's ideas• For more than thirty years had palmed those ideas off

on the world as the product of his own genius