Author: Robert Hyatt
Date: 20:06:47 10/24/01
Go up one level in this thread
On October 24, 2001 at 17:48:26, Tony Werten wrote: >On October 24, 2001 at 15:23:35, Robert Hyatt wrote: > >>On October 24, 2001 at 13:35:48, Tony Werten wrote: >> >>>On October 24, 2001 at 09:40:15, Robert Hyatt wrote: >>> >>>>On October 24, 2001 at 05:38:21, Ricardo Gibert wrote: >>>> >>>>>I originally posted this on CTF by mistake. On Tina's suggestion, I've reposted >>>>>it here. >>>>> >>>>> >>>>>I know very little about bit boards, but I had random thought about what you >>>>>could do with a cpu that has 128 bit words. Does it make any sense to use 128 >>>>>bits instead of 64 bits in a bitboard approach that is analogous to 0x88? Would >>>>>rotated bitboards still be necessary? >>>>> >>>>>Okay, I know these are random thoughts indeed. So what advantage if any would >>>>>128 bits have for bitboards? >>>> >>>>Rotated bitboards would still be useful. But now it would take one operation >>>>to update two of them at once. IE normal and rotated 90 in one 128-bit >>>>word, the two diagonal rotations in another 128 bit word. Would work fine. >>>> >>>>Although 128 bit microprocessors are probably 20 years away or longer... >>> >>>Why 20 ? The amount of bits seem to have doubled every 10 years until now. >>> >>>Tony >> >>Demand. Even supercomputers of today don't use 128 bits. Such values are >>so very big it is not very likely they will be used for quite a while. IE most >>"numbers" simply don't require such large representations, which wastes a lot >>of bus bandwidth transferring 128 bit values when the majority are 16 bits or >>less... > >Could be. I'm quite sure though that's what they said about 32bits when the got >16 bits, and about 64 when they got 32. > >People don't know what they want until there has been a big advertisement >campagne explaining why they really need it. After that it goes fast. > >Tony Just remember that mainstream computing has been basically 32 bits since the very early 60's. That is 40 years. A very few oddballs, from univac and the 36 bit word, to the CDC scientific machines with 60 bits and eventually the Cray with 64. Scientific calculations benefit dramatically from 64 bit operations, when we talk about floating point in particular. And most 64 bit machines support a 128-bit format as well for really extended precision. But mainstream has gotten by with 32 bits for 40 years. I think that once 64 bits have arrived for good, which may still be 4-5 years off, that will likely suffice for another 30-40. Science apps are one thing. Netscape and word processing are different.
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