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clearing bits far away from computation
#4
Ok, so to make sure I'm understanding you correctly, what you're asking/proposing is the application of reversible computing to computing in OA.

Reversible computing is based on the idea that it is possible to design/create computer systems that perform their operations (or as many operations as can be performed) in a fashion that allows you to get an output and then essentially run the computational process backwards. The end result of this is to minimize the amount of waste heat being produced by the computational process. In a 'perfect' system, there would be no irreversible computational processes taking place and no waste heat produced. Although a truly 'perfect' system is not achievable, it is possible to get arbitrarily close to this.

There has been some work in the real world on developing reversible computing hardware and the programs to run them, but the technology/technique is still in its relative infancy.

Based on some stuff I've read on this (not a lot), a reversible computing device could use minimal energy for computation, produce minimal waste heat, but would be slower than an irreversible system since it would have to reverse all it's computations and therefore take twice as long to get X amount of computation done. Although at the speed of modern or future computers, this is unlikely to matter much from an end user perspective in many/most cases.

Does this correctly sum up the concept so far?

Continuing on, and where I'm having a harder time following you...

You seem to be suggesting that it would be possible to have a reversible computer sitting in a room A. That it could do it's thing and produce an output.

Before moving on to the next set of computational operations, the computer must do two things. First, it must copy the output to storage somewhere. Second, it must erase the results of the computation (setting everything to zeros) so that it can get the new set of inputs for the next computation. This is an irreversible process and would normally produce heat.

However, in your scenario the computer would instead transmit the bits making up the results to another room B (possibly located at quite some distance from Room A), where they would be erased, generating heat in Room B rather then in Room A, and thereby helping to keep the computing hardware in Room A even cooler than it would otherwise be as a result of performing reversible computations.

You are also suggesting that the hardware in Room A could also be more compact than it might otherwise be, because it would not need either space or hardware for passive or active cooling (even the much smaller amount that the use of reversible computing would allow), but would only need a means of transmitting the bits making up the result to Room B.

Am I describing this correctly, or am I missing something?

Assuming I am (and I realize I may be missing something vital or totally off base here), the question that comes to mind is how you could literally transport the bits you want to erase from the computer in Room A to the computer in Room B without erasing them from the system in Room A.

My (possibly incorrect) understanding is that in computing when you 'move' bits you are actually copying and transmitting them to a new location while erasing the originals/setting them to zero (thereby generating heat). You can choose not to erase the bits so now you have an original and a copy. But you aren't physically moving anything really so its not like you can suck all the bits out of the computer and having nothing left without actually having erased something.

So, it would seem you would end up with a copy of the bits you wanted to get rid of in Room B, while the original is still in Room A, still needing to be erased. Which would generate heat.

I can certainly see the utility of reversible computation in many situations as a way of producing very efficient computers. Where I'm having a hard time is seeing how you're going to get the bits in the computer to a remote location for erasure/setting to zero without still leaving them all in the original computer still needing to be erased (and generating waste heat in the process).

So, what am I missing and how are you proposing that this would be handled?

Thanks!

ToddSmile
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RE: clearing bits far away from computation - by Drashner1 - 06-07-2015, 09:07 AM

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