The proper way to think of reversible computing is that you just write everything down in a single-static-assignment ledger and never erase anything except for

The proper way to think of reversible computing is that you just write everything down in a single-static-assignment ledger and never erase anything except for the tail end of the ledger. This can be accomplished with a multi-tape machine where writing down a value duplicates the current tape except the changed value. And once you're done with the computation, you can erase one tape at a time, starting with the most recent duplicate. So it can simulate a Turing machine. This implementation isn't as efficient as possible, but it's a good mental model for the absurdity required for reversibility.