Post on 18-Dec-2015
Charles Babbage (1791 - 1871)
• born: 12/26/1791
• son of a London banker
• Trinity College, Cambridge
• Lucasian Professorship
• Mathematician and Scientist
Difference Engine
• 1822 plan for calculating and printing mathematical tables like they were used in the navy
• using the method of difference, based on polynomial functions
Difference Engine
• 1822 design 6 decimal places with second-order difference
• 1830 engine with 20 decimal places and a sixth-order difference
• 1830 end of work on the difference engine because of a dispute with his chief engineer
• 1834 plans for an improved device, capable of calculating any mathematical function
• increase of calculating speed
• never completed
Analytical Engine
Analytical Engine - Architecture
• separation of storage and calculation: – store– mill
• control of operations by microprogram:– control barrels
• user program control using punched cards– operations cards– variable cards– number cards
• more than 200 columns of gear trains and number wheels
• 16 column register (store 2 numbers)• 50 register columns, with 40 decimal digits of
precision• counting apparatus to keep track of repetitions • cycle time: 2.5 seconds to transfer a number from
the store to a register in the mill• addition: 3 seconds• conditional statements
Analytical Engine
First programmer – Ada Lovelace
• Ada Lady Lovelace, daughter of Lord Byron, was working with Babbage on the Analytical Engine
• first ideas of – algorithm representation – programming languages
• already realized:– program loops – conditional statements
Babbage’s meaning in history
• John von Neumann (1903 - 1957): universal computing machine consisting of:– memory – input / output – arithmetic/logic unit (ALU)– control unit
• based on Babbage‘s ideas
• 95 % of modern computers are based on the von Neumann architecture
Babbage’s meaning in history• Howard Aiken (1900 – 1973) developed the
ASCC computer (Automatic Sequence Controlled Calculator) – could carry out five operations, addition,
subtraction, multiplication, division and reference to previous results
• Aiken was much influenced by Babbage's writings
• he saw the ASCC computer as completing the task which Babbage had set out on but failed to complete