Charles Babbage
Babbage's engines were among the first mechanical computers. His engines were not actually completed because he did not have enough money. Babbage realized that a machine could do the work better and more reliably than a human being. Babbage controlled building of some steam-powered machines that more or less did their job; calculations could be mechanized to an extent. Although Babbage's machines were large machines they were organized in a way similar to modern computer architecture. The data and program memory were separated, operation was instruction based, control unit could make conditional jumps and the machine had a separate I/O unit. Ada Lovelace studied how to program them.