64bit computer?

[Dale Farnsworth]

In article <4BE8EDC8.9030009 at cox.net> you write:
> I would like to hear what every one thinks about 64 bit computers. What 
> makes a 64bit computer? Is it just the OS and or does a 64bit computer 
> need a specific kind of motherboard and cpu? Any thing else I have left out?
> I am assuming that applications have to run in 64bit mode or they don't 
> run at all.
> 
> I really would appreciate your view points.

The phrase "64-bit computer" can mean many different things depending
on context.  In the personal computer context, it usually refers to
a computer containing a processor that implements the x86-64 instruction
set developed by AMD and later reluctantly adopted by Intel after their
Itanium processor failed in the market.

Now, it's important to not that the x86-64 (sometimes called amd64)
instruction set is a superset of the x86-32 instruction set, so
x86-64 processors can still run older OSes that only use the x86-32
instructions.  So, to get the benefits of the x86-64 instructions,
you need to run an 64-bit OS.  The 64-bit OSes can usually run 32-bit
applications via compatibility libraries.

-Dale