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Matthiaspaul (talk | contribs) proper capitalization of Hamming distance |
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== Examples of bus encoding to achieve low power==
Following are some of the implementations to use
# ''[[Gray encoding]]'':<ref name="massoud"/> The address lines of a bus in most of the computing systems increase in consecutive numerical values due to [[Locality of reference|spatial locality]]. If we use regular binary coding for the bus, we are not assured of minimal Hamming distance between 2 consecutive addresses. Using Gray codes for encoding the address lines will lead to a Hamming distance of 1 between any 2 consecutive address bus values (as long as spatial locality holds). There are variations to this scheme named Shifted Gray encoding to reduce the delay overhead.<ref name="Shifted_Gray"/>
# ''Sequential addressing or T0 codes'':<ref name="Zero-Transition_1997"/> In case of address bus, due to spatial locality that exists in programs, most of the transitions involve changing the address to the next consecutive value. A possible encoding scheme is to use an additional line, INC, in the bus indicating whether the current transition is the next increment address or not. If it is not a consecutive address, then the receiver can use the value on the bus. But if it is a consecutive address, the transmitter need not change the value in the bus, but just assert the INC line to 1. In such case, for a continuous addressing scheme, there is no transition at all on the bus, leading to a bus activity factor of 0.
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