Automan_Empire - 2:44 am on Nov 22, 2012 (gmt 0)

"Valve" is indeed another name for "vacuum tube." Most tubes are analagous to a transistor; amplifying a weak signal but using a hot cathode.

The dekatron is a different animal, a decade counter. It is filled with neon, argon, or hydrogen, and uses cold cathodes. Inputting clock pulses causes the glow, thence output, to jump to the next cathode. They can count up or down. There's an interesting wiki article on them, and you can buy dekatron "spinners" on auction sites. Also, check out nixie tubes if vintage tech rings your chimes.

My grandfather worked on vacuum tube computers in the '50s. He told me that tubes numbered in the hundreds or more, and you were lucky to get 15 minutes of use before a tube failed, though the fault tracing systems and methods were surprisingly good.