Hummmm,, All that heat from the valves and it just went to waste. Maybe Colossus could have generated enough heat to boil water to run a steam engine that in turn turned a dynamo to make the necessary electricity to heat the valve elements! Wow! Perpetual motion at last and people have been working on it without success since the middle ages. Jesse the crazed REDNECK machinist in Tennessee, USA Chris, As a mechanical engineer I find it difficult to warm to computers even though I am told by an "early nerd" friend of mine that it was actually quite easy to warm to them because the heat from all those valves was horrific! Cheers, Barrie MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.