Re:X86 mov is turing complete: mov-only compiler
by gnu8 on Sunday June 21, 2015 @12:28AM
(#9752177)
This is almost surely a dumb question, but what would happen if someone made a processor that only executed mov instructions, which would be extremely simple, and presumably would be really goddamn fast. Would that be competitive with today's fastest CPUs? If it were, what would be the advantages and disadvantages of this design?
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Re:X86 mov is turing complete: mov-only compiler
by gizmo686 on Sunday June 21, 2015 @12:43AM
(#9752213)
Well, Turing machines do not have random access memory (which changes the big-theta complexity of algorithms), and that operations such as multiplications would be complicated and multi-cycle, whereas conventional CPUs can easily parralize them.
If you were comparing the performs of mov-only programs, a specialized cpu would likely be faster. Otherwise, there is a good reason we do not actually use Turing machines.
Re:X86 mov is turing complete: mov-only compiler
by sklogic on Sunday June 21, 2015 @11:08AM
(#9753686)
An extreme example:
http://laughtonelectronics.com/Arcana/One-bit%20computer/One...
A bit less extreme: http://www.sccs.swarthmore.edu/users/06/adem/engin/e25/final...
Re:X86 mov is turing complete: mov-only compiler
by userbinator on Sunday June 21, 2015 @08:15AM
(#9753116)
what would happen if someone made a processor that only executed mov instructions, which would be extremely simple, and presumably would be really goddamn fast.
The laws of physics get in the way. It's essentially the same reason why clock frequencies have stopped going up.
Re:X86 mov is turing complete: mov-only compiler
by 0xe2-0x9a-0x9b on Monday June 22, 2015 @03:00AM
(#9756635)
"a processor that only executed mov instructions, which would be extremely simple"
I believe such a CPU wouldn't end up simple due to competition for better performance. It would end up being more complex than x86 CPUs.