Early Mechanical Computers Flashcards
Who were some of the people behind the early mechanical computers and when did they live?
Wilhelm Schickard (1592 – 1635) Blaise Pascal (1623 – 1662) Gottfried Leibniz (1646 – 1716)
How did these machines look and what was their general functioning like?
kinda looked like giant boards with cogs and memory displays to show current numbers. wheel mechanism representing each digit would get turned clockwise or counterclockwise for addition and subtraction respectively
What was the one major challenge faced in the design of all the early calculating machines (Schickard – Grillet)?
Propagating the carry
How were Napier’s bones employed in William Schickard’s calculator?
aeg
How did carries get propagated from one digit to another in William Schickard’s calculator?
result of additions to a previous common passed in next column using single toothed gear which after passing 0 (10 toothed gears)would shift the next gear forwards (addition) or backwards (subtraction)
What was the limit on the carry and how was it dealt within William Schickard’s calculator?
age
What was the eventual fate of Schickard’s calculators?
- one of them was given to kepler
- unknown what happened to schickard’s copy
– It was believed that Schickard’s family was wiped out in a plague and the was unceremoniously disposed of
Who invented the first true adding machine?
William Schickard
What are events from Pascal’s early child hood background, the events that lead up to the design and eventual development of his Pascaline and the end of his life?
- Born in Southern (Clermont) France
- Home schooled’ in the basics of reading and writing by his father Etienne Pascal.
- Family was tax collectors so the motivation for the pascaline was to automate the process
- life changing dream in 1650
How is the Pascaline is operated in order to perform an operation and what operations were possible?
output windows and input dials divided into 10 spokes. place stylus in-between spokes and rotate clockwise to input a digit. entering multiple numbers consecutively causes there sum to show.
- use 9’s complement for subtraction
After addition values must be cleared. this is done by setting all accumulators to 9 and then incrementing lowest digit used in previous calculation
How is a carry is propagated between digits?
falling weight mechanism that increments the next cog in line. carry pins lift fork attached to weight progressively higher as accumulator approaches 9 and
What was the eventual fate of Pascal and his machines?
- Several machines were produced but sales weren’t profitable
- Few survive to today.
- They were quite delicate
How was the stepped drum implemented in Leibniz’s calculating machine?
ags
How did the partial carry approach for Morland’s adding (subtracting) machine work?
age
What are common attributes of the early mechanical computing devices?
– Set up:
• Allows the number to be entered – Selector:
• Determines the type of operation (addition, subtraction) – Registering mechanism:
• Indicates the value of a stored number (result) – Carry Mechanism:
• Determines that any carries are handled properly – Control mechanism:
• Ensures that the gears are properly aligned at the end of each operation (avoid false results and jamming)
– Erasing mechanism:
• Reset the result register between operations
