Here I go again...

[Chainsaw Aardvark]

There was an article not too long ago about IBM making the smallest world's magnetic computer memory bit - twelve atoms. Smaller than that, and quantum effects messed up its ability to store data. Of course, it required a tunneling microscope, and heating/transfer rates mean its probably not practical.

We could probably make electronic computers without quantum mechanics. We could probably even step past vacuum tubes to transistors, even on to microchips - but probably not with the same sort of Moore's law doubling. That is just my guess, however. It may be quite possible that all radio wave transmitters - even the spark gap transmitter (the tube's predecessor) relies on a quantum effect, just never described as such.

Of course, a world without microchips is an interesting one indeed, even without the retro Victorian veneer. Microchips are what made unmanned satellites smaller and cheaper, and thus a better alternative to manned space missions - computers killed the need for space stations. Advanced computers (and modeling made with them) and miniaturized components shrunk the size of nuclear weapons - making ICBMs possible, as wells as most guided weapons. No microchips, and modern air raids would look like something out of WWII, just with faster aircraft.

[Onix]

Transistors rely on quantum mechanics to function. Put another way, they could not be explained by science until quantum mechanics were more fully understood. Of course the same is still true of the brain.