Tom Flowers

Today marks the birthday of Dr Tommy Flowers, the builder (somewhat w/ Alan Turing) of the first modern ie digital computer. It was constructed during WWII here in UK, to decrypt German operations messages, and christened 'Colossus'. It contained 2400 thermionic valves (picture from Wikipedia) each several centimetres long, so its name was suitably apt! These valves were basically operating as switches (even though they were primarily designed as amplifiers), and serve the same role that transistors on a chip do in modern microprocessors, though these latter contain many millions on a tiny wafer.
The Colossus represented a real advance in computing though, as it was the first time that a machine had been built using electronic rather than mechanical switches for greater speed and flexibility. It was this potential that Flowers recognised.

From http://www.ivorcatt.com/47c.htm
"At the time I had no thought or knowledge of computers in the modern sense and had never heard the term used except to describe somebody who did calculations on a desk machine."

"Colossus was useful in more than one way, and there were even demonstrations applying it to number theory. But these demonstrations were more notable for their ingenuity than for their effectiveness."