Author: Ricardo Gibert
Date: 23:47:16 02/15/00
Go up one level in this thread
On February 16, 2000 at 02:12:21, Eugene Nalimov wrote: >On February 16, 2000 at 00:26:19, Christophe Theron wrote: > >>On February 15, 2000 at 22:45:28, Tom Kerrigan wrote: >> >>>On February 15, 2000 at 20:42:43, Ricardo Gibert wrote: >>> >>>>MIPS VR4121 is a 64 bit CPU according to NEC. Look at >>>>http://www.nec.com/Semiconductors/categories/679/981008.html >>> >>>You're right... Hmmm... I wonder what the "64 bit" measures. Maybe memory >>>interface? Because it seems pretty silly to have a full-blown 64-bit embedded >>>processor, when your desktop machine is still 32-bit... >>> >>>-Tom >> >> >>Wait a minute. The VR4121 processor claims pin-to-pin compatibility with the >>VR4111. And the VR4111 is a "false 64 bits" processor. Operations can be done on >>64 bits internally, but the data bus size is 16 or 32 bits. That is, there is a >>serious bottleneck between the processor and the memory when it comes to 64 bits >>values. >> >>I'm not even sure that this processor really supports clean 64 bits operations. >>All the docs I have mention 16 and 32 bits long instructions. How do you perform >>a move immediate with a 64 bits value if your instruction length is limited to >>32 bits? > >IBM/360, as well as IBM/370, also have no instruction "move immediate 32-bit >value"; if you want to load literal that is longer than 12 bits, you have to >load it from memory. Nevertheless it is true 32-bit processor. > >At that MIPS processor, loading/storing 64-bit values can be slower than 32-bit >values - but total impact on performance would be small enough. Small size of >cache is much more important, but I believe Crafty would perform as it's running >on P90-120. Windows 95 Pentium P5-120 159.4 Drystone MIPS Win CE VR4121 131mhz 174 Drystone MIPS So your prediction is not bad. > >Eugene > >>And don't count on the 8Kb internal L1 data cache to store all the data needed >>by Crafty... >> >>A bitboard program looks like a poor choice for this architecture. >> >> >> >> Christophe
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.