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Subject: Re: misunderstanding about PC cards (deep blue)

Author: Tom Kerrigan

Date: 23:30:52 06/27/98

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>And if the DB hardware is too big or hot to be inside an ordinary PC, it can be
>placed in an external box with an expansion card to interface with it.  But
>would the PCI bus present a bandwidth bottleneck when compared with the
>processor and DB chip speed?  Or would the DB hardware have its own processor
>which does the coordination between the DB chips.

The new 3D chips coming out are probably at least as big and hot as a DB chip,
and cooling them isn't a huge problem.

Anyway, even if the PCI bus doubled the amount of time the chip took to search a
position, it would still be a tremendous gain. Let's consider these random-ass
figures:

32 bit PCI bus, 33 MHz transferring a position (say, 256 bytes) = 30 ns *
(256/4) = 1920 ns * 2 (miscellaneous overhead) =
3840 ns to get a chip started on a position

time for a chip to search the position:
4 ply search in 100,000 nodes (no null move, etc.)
say, 50,000 evaluations (1.5 clock cycles)
another 5,000 move generations (4 clock cycles)
clock cycle = 10 ns (100 MHz) ->
950000 ns to search a position

So, taking these phenominally conservative numbers, transmitting the position
still only takes 0.5 percent of the time it takes to search it...

Cheers,
Tom



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