The Difference Engine was an automatic,
mechanical calculator designed to tabulate polynomial functions. difference
engine can compute many useful sets of numbers. This machine used the decimal
number system.Babbage invented
two difference engines these are Difference engine 1 and Difference engine 2. In the Babbage design, one iteration i.e.
one full set of addition and carry operations happens once for four rotations of
the crank. Odd and even columns alternatively perform an addition in one cycle.
The sequence of operations for column n is thus:
- Count up, receiving the value from column n + 1 (Addition step)
- Perform carry propagation on the counted up value
- Count down to zero, adding to column n − 1
- Reset the counted down value to its original value
Steps
1,2,3,4 occur for every odd column while steps 3,4,1,2 occur for every even
column