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I'm wondering... What happens when I do a reversible computation where no information is lost, does cutting the power on the unit create heat?
by physix 1y ago
I'm wondering... What happens when I do a reversible computation where no information is lost, does cutting the power on the unit create heat?
- bee_rider 1y agoI guess it would depend on the physical design of the compute elements (reversible computing is generally associated with post-CMOS tech). But, cutting power doesn’t necessarily reset a machine in general… think of a mechanical computer, cutting power removes the ability to change state.
- hyghjiyhu 1y agoIdk how accurate it is by my mental model of this would be that electricity is like a liquid and when you flip the switch, it drains out of the components creating heat through friction.
- cwillu 1y ago“Cutting power” is a thing because current computers require a periodic (and rather frequent) refresh to maintain the state of the system (primarily, but not exclusively, RAM). And indeed, one useful tactic to maintain that state when you need to cut the power for some reason is to supercool the ram so that it doesn't dissipate its charge as fast, basically making the system approach that ideal world.
- thrance 1y agoA fully reversible computers would consume no power whatsoever, so wouldn't require power to function. Instead, you would need power to (re)initialize its state, or to copy the results of its computations to e.g. your monitor. An unplugged reversible computer would be free to compute (and uncompute) its bits perpetually, unconcerned about the rest of the world. The functional programmer's dream, in a sense.
- physix 1y agoThanks for that and the preceding comments. I was thinking about the possible paradox of getting a reset for free. But, the cost invariably comes at some point, e.g. when you restart and need to reset your state.