Re: Linux-2.0.11

Stephen C. Tweedie (sct@dcs.ed.ac.uk)
Wed, 7 Aug 1996 00:04:43 +0100


Hi,

On Tue, 6 Aug 1996 08:49:38 -0400 (EDT), RHS Linux User
<trouble@cyberchat.net> said:

> i have a Intel 6x86 P120Mhz CPU and 64 bit mother board, pci based
> made by amptron.... is there going to be a 64-bit clean version for
> these 64 bit systems that will recognize the fact that they are
> compiling for ie a 686 class 64 bit system..... and such......?

It is not a 64bit system.

Most modern cpus can rapidly become memory-bound. They can compute
very fast, so to provide a fast data stream to the cpu they need much
more rapid access to main memory than normal dram can support. One
way of increasing the speed at which memory is shuffled between the
dram and the cache, or between the cache and cpu, is by transferring
more bits in a single clock cycle.

The 64-bit label for pentium or 6x86 motherboards just refers to the
speed at which memory gets shuffled around the system. As far as the
software itself is concerned, it's still a purely 32-bit processor;
with the exception of some high-precision floating point values, the
cpu always accesses data from its cache 32 bits at a time. The
operating system doesn't need to know how the motherboard is moving
memory around internally.

Cheers,
Stephen.

--
Stephen Tweedie <sct@dcs.ed.ac.uk>
Department of Computer Science, Edinburgh University, Scotland.