It would be good if someone who understands this topic well -- and I do not -- would explain why bit-level parallelism has run out of steam. Why not 128-bit or 256-bit processors? Is it just that the benefits of bit-level parallelism apply mainly to arithmetic, and 32- or 64-bit word sizes comfortably accommodate numbers within the range of most calculations? Or is there another reason?
@Eodell There are 128-bit and 256, even 512-bit processors, but those are mathmatical registers. General purpose registers which can be used to point to memory addresses are still not exceeding 64-bit because we hardly have one tarabyte of memory for CPUs. Dannyniu (talk) 11:39, 15 June 2016 (UTC)