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Barcamp Cambridge presentation on Charles Babbage and his Difference Engine
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Charles BabbageDifference Engines
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
My background
• Nathan Lisgo
• BSc Hons Computing
• Web Developer for over 10 years
• PHP, MySQL, Javascript, Flash
• Sept 2009 joined Panoetic
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Objectives
• Bio of Charles Babbage
• His Quest
• Pioneer of the computer?
• Doron Swade takes up the baton
• World exclusive
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Charles Babbage • 1791 - 1871
• Age 8 recovered from life-threatening fever
• 1810 - Arrived at Trinity College, Cambridge
• 1812 - Founded Analytical Society with peers
• 1812 - Transferred to Peterhouse, Cambridge
• 1814 - Received honorary degree without examination
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Anything for science
• Baked himself in an oven at 265 F
• Lowering himself into the mouth of a volcano
• Walking on water
• A restless innovator
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
The character
• Radical, bold and defiant
• Protest was preferred to persuasion
• Being right meant it was ok to be rude
• Friends could do no wrong, his enemies could do no right
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
His Quest7
Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
I wish to God these calculations had been executed by steam
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Four sources of error
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• Calculation
• Transcription
• Setting of loose type
• Verification
Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
The excitement of the enquiry had an unfavourable effect upon
my bodily health; and I was recommended to abstain entirely for a time from all thought of the
‘Calculating Engine’
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
It was certainly fortunate for me, both at this period, and at many times, that I had no sufficiently distinct
view of the multitude of difficulties...which were destined to attend its course. Had these not opened upon me by degrees, I might perhaps never have
ventured on its execution.
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Planning
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• Designs
• Prototypes
• Diversions
• Redesigns
Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Difference Engine #213
Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Pioneer of the computer?
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• On switch - crank
• Micro program - stack of cams controlling operation of all parts
• Registers - 7 stacks of 31 rotating digits store and change numbers during calculation
• On screen display - results column
• Printer - prints on paper and stereotype plates
• Fault detection - machine was designed to jam rather than risk delivering an incorrect result
Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Printer
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• Variable line height
• Variable column width
• Gaps between groups of lines
• 1, 2, 3 or 4 columns
• Stereotypes in 2 font sizes simultaneously and adjusts line height accordingly
• Automatically line wrap or column wrap
Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Doron Swade
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• Museum curator
• Author
• Specialises in History of Computing
• Authority on Babbage
Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Difference Engine #2realised
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Authenticity
• Missing information: Methods of manufacturing, tolerance and finish
• Drew knowledge from 19th century machines
• Composition analysis on metals used by Babbage
• Resist the charge “You built the engine, but Babbage could not have”
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Finite Differences
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0 2 -1 4
1 1 3 4
2 4 7 4
3 11 11
4 22
x 2x²-3x+2 Diff 1 Diff 2
Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
No substitute for seeing the machine run
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Barcamb 2010Nathan Lisgo | Technical Director | Panoetic Ltd
Questions?
http://panoetic.com@nlisgo
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