There is a lot of hype about 64-bits. I believe 'crafty' is basically
a 64-bit calculator, so would in principle at least run faster on
64-bits (I'm sure Robert will clarify matters).

But be aware that any references to memory ("pointers") take up 8
bytes on a 64-bit machine, compared to 4 on a 32-bit machine. So fewer
memory references can fit in the cache, so the cache hit rate goes
down.

I find the whole thing about 64-bit a bit of a joke really. One
magazine (Personal Computer World published in the UK) recently stated
that Apple were the first to put a 64-bit computer on the desktop.
That is total junk, as I know Sun did it nearly a decade earlier and I
don't think Sun were the first.

The machine I'm sending this message from is an oldish 64-bit computer
from Sun (Ultra 80, 4 x 450 MHz CPUs with 4 MB cache each, 4 GB RAM).
The operating system (Solaris 9) fully supports 64-bit hardware. Yet
if one checks how most of the executables are linked (using the UNIX
'file' command), one sees that most are in fact 32-bit, not 64-bit.
Sun do that for performance reasons - why make executables larger, and
get lower cache hit rates unless you need to ???

64-bit machines are neither new, nor any benifit at all, for the vast
majority of tasks. Chess might well be an exception to that (I think
it is), but before shelling out lots of $$$$'s for 64-bit machines,
check whether there is going to be any gain at all.

I know someone who built crafty on a 64-bit Sun and found some, but
quite a small benifit. In this case the SPARC assembly code, that
forms part of crafty, was written for 32-bit machines, so the main CPU
intensive bits don't benifit from 64-bits. No doubt if Sparc.s was
re-written to exploit 64-bit registers on Suns, crafty would run
faster, but that would not be a trivual task for anyone. On x86 I
guess more effort will be put into making 64-bit optimised versions.
Sun have rather lost their way in the workstation market.

Just a few thoughts - before you go out buying 64-bit hardware!

If you fancy playing with 64-bits, get yourself a Sun Ultra 1 on eBay.
This one sold for less than $30 !!!

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3064866384&categor...
You can download Solaris 9 for free, although you are supposed to buy
a license after a 60-day trial period (not that it stops working or
anything).

64-bits is very hold hat - don't get caught up in all the hype
</soapbox>

Dr. David Kirkby PhD CEng MIEE