Reversible computer designs people actually consider building do a small bit of irreversible computation copying end results of the reversible computations into irreversible memory before rolling back the reversible computation. Perfectly reversible computations are a bit useless since they erase their results when they start rolling backwards.
It seems relevant to the comment that “if memory is reversible, it’s not memory”. Reversible computers have reversible memory.
Reversible computer designs people actually consider building do a small bit of irreversible computation copying end results of the reversible computations into irreversible memory before rolling back the reversible computation. Perfectly reversible computations are a bit useless since they erase their results when they start rolling backwards.
You can erase some of their results without erasing others, of course.
Nobody says you have to run a reversible computer backwards.
A big part of the point is to digitise heat sinks and power management. For details about that, see here.