Modern computing turns 66 this year. It was in June 1946 that ENIAC, the first general purpose computer, was turned on. That got me thinking. If the transistor had never been invented, how large would a modern tube powered computer be?

ENIAC weighed 27 tonnes for its 17,468 tubes and other components.

So I Googled vacuum tube weights and came up with a rudimentary number of about 150g per tube. This was for a large triode that appears similar to the ones used in ENIAC. Tube Diodes and triodes share a similar function to modern day transistors. They amplify and gate electrical signals.

My computer has an AMD Phenom II X4 955. It clocks in at 758 million transistors. At 150 grams a piece for each tube, this comes to a whopping 113,700 metric tonnes. That's heftier than a Nimitz Class aircraft carrier.

ENIAC was big...

The original iPhone 4 had about 200 million transistors. It would be about half the size of the RMS Titanic.

Intel's fastest consumer chips, the Core i7 hexes, have about 2.270 billion transistors. It would weigh in at 340,500 tonnes The weight of three of those aircraft carriers.

A vacuum tube 6-core Core i7 would tip the scales, larger than 3 aircraft carriers

Of course this is just for the tubes alone. That doesn't include the relays, wiring, resistors, capacitors, and mounting racks to hold it all together. It's pretty staggering how far we've come in the last half century of computing.