Author: Robert Hyatt
Date: 20:20:54 04/07/00
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On April 07, 2000 at 12:04:47, Tom Kerrigan wrote: >On April 07, 2000 at 08:07:56, Robert Hyatt wrote: > >>>(another 5 cycles). So doing SEE takes 10/2=5 times as long. This ignores the >>>fact that the SEE is probably much more expensive than 1 cycle, and the added >>>complexity/time of saving the list of captures/SEE values and then sorting them. >>Again, as I said, if I was designing a circuit to do a SEE, it would _still_ >>be faster than software SEE. And it could include as much as we wanted in >>terms of not overlooking pinned pieces or whatever... and _still_ run fast >>enough that it would be totally unnoticable in a chess engine... IMHO of >>course. > >I still disagree. Didn't DB do a quick evaluation in ~4 cycles? So going back to >my example, the time to search 2/5 capture moves using MVV/LVA is: > >generate moves = 2 * 2 >make moves = 1 * 2 >eval = 2 * 8 >=> 22 cycles > >And if you use SEE: > >generate moves = 2 * 5 >SEE = 5 * 5 I don't see 5*5 cycles in SEE. I see 5 to enumerate the capturing pieces, 5 to minimax the score. 10 total... That is definitely cheaper than searching a node, which takes 10 clock cycles in DB. Because in the above case you would have to search up to 10 nodes (5 captures per side) which is 100 clocks. >make moves = 1 * 2 >eval = 2 * 8 >=> 53 cycles > >So I bet SEE would slow the chip down by at least a factor of 2. I think that's >pretty noticable. > >>Not when you read the details about the _last_ ASIC. They added kpk endgame >>database to simply fill out the remainder of the chip... which sounds like >>space wasn't a problem... especially considering they used under 50% of the >>total eval hardware in the last version of DB, which suggests that he also added >>a _lot_ of feature detection hardware that was also done just to fill out the >>chip and was not used due to lack of time to test it. > >Possibly. The PKP database doesn't impress me very much because it can probably >be extremely dense. I wouldn't be surprised if the move generator was larger >than the database. > >-Tom
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