> you need at least n bits of state in order for a program to run for 2^n cycles before halting Only for a non-embedded system. Prisms are embedded: you have

> you need at least n bits of state in order for a program to run for 2^n cycles before halting Only for a non-embedded system. Prisms are embedded: you have to illuminate them to get them to do anything interesting. So to compare apples and apples you have to consider a case like: connect a microphone to your computer and compute the SHA512 hash of the audio stream. That will require only O(1) space but will never halt as long as the microphone is plugged in.