Difference Engine No. 2 (reconstruction from 1830s design) A more complex difference engine designed by Babbage. This design was never fully completed, due to Babbage's fights with various individuals and with the British government, which partly sponsored the effort.
The Harvard Mark IV, built in the early 1940s, has many features borrowed from the Analytical Engine's design. If it had been built, the Analytical Engine would have incorporated memory, a central processor or "mill an input system, and even a graphical plotter for producing.
The left image shows the Hollerith punched-card system used in the 1890 census, and a 1920s era punched-card system that created data for these mechanical calculators. Hollerith later founded IBM, the main computing company of the 20th century.
The most advanced of these systems included all the components found in a modern digital computer. However, they were mechanical instead of electrical - turned by crank, or by a steam engine, as in the larger Analytical Engine.
His first one was an analog device rather than digital - a sort of electric slide rule that did not use symbol processing the way a modern digital computer (and Babbage's engines) does. A tanasoff-Berry Computer (1937) Unlike the Differential Analyzer, the Atanasoff-Berry computer used.