Hardware First Generation (Mechanical/Electromechanical) Calculators Antikythera mechanism , Difference engine , Norden bombsight Programmable Devices Jacquard loom , Analytical engine , Harvard Mark I , Z3 Second Generation (Vacuum Tubes) Calculators Atanasoff–Berry Computer , IBM 604 , UNIVAC 60 , UNIVAC 120 Programmable Devices Colossus , ENIAC , Manchester Small-Scale Experimental