Difference Engine:

   Babbage

   Colossus

   John von Neumann

   Alan Turing

   ENIAC

   Mauchley and Eckert

   Transistor

   Integrated Circuits

   Univac

   Altair

   First IBM PC

   Push-Pull impact on advancements in science

     ♦  impact of space race (pull)

     ♦  Innovative products (push)

     ♦  The Internet (pull)