The world's first programmable computer, Colossus, was built at Bletchley Park in the UK during WW2 to break German codes created by the Lorenz cipher machine. It was designed by a Post Office engineer called Tommy Flowers and it used literally hundreds of valves (tubes). They built a Mk2 that used even more valves. Several more Colossus machines were built before the end of the war. Then Churchill ordered that they and all the plans should be destroyed for security reasons. Fortunately engineers have a habit of hanging onto bits and pieces so you can visit Bletchley Park today and see a recreated Colossus in full working order. It gets damn hot in that room with all those valves! Sorry for the diversion -- back to the amp debate.