Nathan Lisgo introduces himself and provides an overview of Charles Babbage and his work developing early mechanical computers called Difference Engines. The document discusses Babbage's background and personality, his quest to build the engines, the challenges he faced, and how his work to develop the Difference Engine #2 was later realized by the building of a working replica by Doron Swade and his team. It aims to give attendees a bio of Babbage, his pioneering work in computing, and a world exclusive on the authentic rebuilding of his unfinished Difference Engine #2.

1. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Charles Babbage
Difference Engines
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2. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
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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3. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Objectives
• Bio of Charles Babbage
• His Quest
• Pioneer of the computer?
• Doron Swade takes up the baton
• World exclusive
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4. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
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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5. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
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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6. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
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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7. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
His Quest
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8. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
I wish to God these calculations had
been executed by steam
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9. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Four sources of error
• Calculation
• Transcription
• Setting of loose type
• Verification
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10. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
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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11. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
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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12. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Planning
• Designs
• Prototypes
• Diversions
• Redesigns
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13. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Difference Engine #2
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14. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Pioneer of the computer?
• 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
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15. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Printer
• 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
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16. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Doron Swade
• Museum curator
• Author
• Specialises in History of
Computing
• Authority on Babbage
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17. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Difference Engine #2
realised
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18. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
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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19. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Finite Differences
x 2x²-3x+2 Diff 1 Diff 2
0 2 -1 4
1 1 3 4
2 4 7 4
3 11 11
4 22
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20. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
No substitute for seeing the
machine run
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21. Nathan Lisgo | Technical Director | Panoetic Ltd Barcamb 2010
Questions?
http://panoetic.com
@nlisgo
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