RTL Logic

Which brings up something I've wondered about for a long time: what goes wrong with TTL when powered at other than 5V? "It doesn't work", yes, but _why_? I've got schematics for many of the simpler circuits in my data book, and I can't see anything there that I wouldn't expect to work equally well at anywhere from 3 volts or so up to the point at which either currents get so high that dissipated power cooks something or insulating layers break down, whichever happens first. So there's obviously something I don't quite understand going on, and there are few better places to learn such things than here. :-) Besides, the data book itself, never mind the parts described in it, is on topic by now. Heck, I personally used it in the late '70s. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B