On 08/23/2011 10:37 PM Drew wrote:
>>> What determines if it's a 64 bit machine? Dual core?
>> Dual core = 2 CPUs effectively.
>> Quad core = 4 CPUs on the same piece of Silicon
>>
>> 64 bit = more advance instruction set which replaces all the older 32
>> bit instruction set CPUs. 64 bit is more modern than 32 bit and that is
>> the way software is going.
>
> 64bit doesn't specifically make it "more advanced." 64bit CPU's just
> support for a larger memory addressing space then 32bit CPU's, beyond
> the 4GB limit of 32bit addresses.
>
>
64-bit processors can deliver 64 bits of data at a time to all
peripherals, not just memory. By contrast, 32-bit processors can
deliver at most 32 bits to any peripheral, then as a second step deliver
the next 32 bits. So, AOTBE, it takes twice as long to shoot data down
the bus. That's outgoing. Same applies to data coming into the
processor. I haven't looked up and compared the lists of instructions
on 32- vs. 64-bit CPUs, but generally the bigger processors have more,
and more sophisticated, instructions. This means, e.g., that instead of
taking 20 steps to do a calculation on a 32-bit CPU, it might be done in
5 steps on a 64-bit. There might also be larger L2 and L3 caches on the
larger processors (but this also varies within the 32-bit and within the
64-bit families).
All that said, I still use a five-year-old 686... as both a server and a
client. It runs apache, mysql, and several other servers apps, plus the
full range of client applications... most of the time I'm using about 2%
of the CPU's power. I've worked in places where I've had access to 80
or so servers and most of them never used more than 5% of their CPU's
processing time... kind of a waste... in several ways. So unless you
really need the big, f*'ing CPU, why diddle away your cash?
--
War is a failure of the imagination.
--William Blake
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