A B rie f In tro d u c tio n to th e H is to ry o f - - PowerPoint PPT Presentation

A B rie f In tro d u c tio n to th e H is to ry

• f C
• m

p u tin g

ANU Faculty of Engineering and IT Department of Computer Science

COMP1200 Perspectives on Computing

March 2002-5 Chris Johnson

intro to history of computing (1): Big Ideas 2

In tro to h isto ry o f co m p u tin g – 1

1.

The Big Ideas in computing before and after electronics

2.

The early years of electronic computing

3.

3 or 4 Generations of computing technology

intro to history of computing (1): Big Ideas 3

W h a t’s h isto ry g

• t to

d

• w

ith co m p u tin g ?

it’s still happening we all need to know

how technology has changed (and why) how fast it has changed and is changing what effect this has on people (and who chooses)

intro to history of computing (1): Big Ideas 4

1 . B ig Id e a s – b e fo re a n d a fte r e le ctro n ic co m p u tin g

“Computing is no more about the study of computers than astronomy is about telescopes” [Edsger Dijkstra] “Computer Science is not equal to programming” [Andre deHon] but let’s get some background history about computers (hardware) and programming (software)– what are the Big Ideas here?

intro to history of computing (1): Big Ideas 5

1 . B ig Id e a s – b e fo re a n d a fte r e le ctro n ic co m p u tin g

The Big Ideas are associated with computing machines– hardware 2 algorithms and data– software 3 access and distribution– networks 4

• rganising people and processes – inform ation

system s and software engineering

intro to history of computing (1): Big Ideas 6

1 . B ig Id e a s – b e fo re e le ctro n ics

numbers can be represented by written symbols MCMXLVII 8 3 1 algorithms exist and can be written down e.g. multiplication to any length 8 3 1 x 4 2 1 6 6 2 3 3 2 4 (+) 3 4 9 0 2 similarly: Newton’s method for square root (actually invented by the Greeks)

what’s the algorithm?

intro to history of computing (1): Big Ideas 7

1 . B ig Id e a s – b e fo re e le ctro n ics

Al-Khwarizmi ... Algebra Baghdad 9th century Fibonacci arithmetic and algebra 12th century Pisa

intro to history of computing (1): Big Ideas 8

1 . B ig Id e a s – b e fo re e le ctro n ics

mechanical objects can represent numbers

intro to history of computing (1): Big Ideas 9

1 . B ig Id e a s – b e fo re e le ctro n ics

mechanical processes can implement algorithms

20th century copy of Babbage’s Difference Engine (4000 parts) 1956 Melitta calculator

intro to history of computing (1): Big Ideas 10

2 . B a b b a g e ’s D iffe re n c e E n g in e

18th and 19th century Europe had great need for mathematical tables

intro to history of computing (1): Big Ideas 11

2 . B a b b a g e ’s d iffe re n c e e n g in e

Many functions can be approximated by polynomials The Method of Differences is a practical method of calculating intermediate values more quickly than applying the full formula from scratch at every point. Applications in

• Ephermeris Tables for navigation
• artillery range-charge-angle tables

The Difference Engine was not built in its full form until 1991

intro to history of computing (1): Big Ideas 12

2 . d iffe re n ce s – so la r d e clin a tio n (N

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0.02 0.00

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17.13 8 17 217 5 August

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17.40 24 17 216 4 August 0.00 0.00

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17.67 40 17 215 3 August 0.00 0.00

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17.92 55 17 214 2 August

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18.17 10 18 213 1 August 2.98 0.98

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18.42 25 18 212 31 July

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18.67 40 18 211 30 July 0.99 0.99 0.77 19.90 54 19 210 29 July 0.00 0.00

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19.13 8 19 209 28 July 0.00 0.01

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19.35 21 19 208 27 July

• 0.01
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19.57 34 19 207 26 July

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19.78 47 19 206 25 July 20.00 20 205 24 July 3rd 2nd 1st decimal minutes degrees day of year diffs. D+E/60 E D

intro to history of computing (1): Big Ideas 13

2 . c

• m

p u tin g b e fo re e le c tro n ic s

1890 Herman Hollerith applied Jacquard-style punched cards to represent data for the US Census, processed by purpose-built selection and calculation machines

• > founded IBM

Jacquard in 18th Century had used holes punched in sequences of cards to control weaving looms for fancy patterns– the term is still used for fabric with patterns in the weave

intro to history of computing (1): Big Ideas 14

1 . m

• re

B ig id e a s– b e fo re e le ctro n ics

algorithms can be studied as mathematical objects in themselves computability: mathematical proof that not everything can be computed in principle

mathematician Godel 1930 mathematician Turing 1936 – “Turing machine” model of computation

1940s: a computer is a person who does calculations calculators have separate control and data

intro to history of computing (1): Big Ideas 15

1 . B ig Id e a s – e le ctro n ic co m p u te rs

electronic valves can be used to represent and store numbers 1940s: Alan Turing and others algorithms

• represented as programs -

can be kept in the same storage as their data 1945 John von Neumann gets the credit but others were involved [Brookshear p. 76]

The architecture of the stored program computer is now commonly called the von Neumann architecture John von Neumann 1903-1957

intro to history of computing (1): Big Ideas 16

1 & 2 . B ig Id e a s -co m p u tin g w ith e le ctro n ics

the stored program computer

intro to history of computing (1): Big Ideas 17

2 . B ig Id e a s - th e sto re d p ro g ra m co m p u te r

Challenge: Why is the ability to store the program in memory so important? Reading Brookshear 0.1, 0.2, 0.3, 2.1 and COMP1200 online Notes for the History module.

W ho was Turing? von N eum ann? W hat w ere they doing w hen they “invented” electronic com puters?