Subject: Re: Inquiring minds want to know.
To: None <firstname.lastname@example.org>
From: Aaron J. Grier <email@example.com>
Date: 05/21/2003 14:22:29
On Sat, May 17, 2003 at 11:15:08PM +1000, Collin Baillie wrote:
> I'm wondering if anyone out there can extoll the differences between
> the Alpha 64-bitness and the new Opterons. I know the opteron is a
> glorified x86 box, but how does it stack up (theroetically) against
> the Alpha?
I'm curious about this, too. I seem to recall that AMD used some of the
same bus interfacing that Alpha did.
> And while I (kind of) know the difference between Little Endian and
> big Endian, I've never really learned what the real difference is and
> it might be advantageous to have one or the other.. Is anyone
> interested in explaining this to me as well?
if you're on a little endian system, if you have the address of a
variable and want the lowest byte, you just do a byte read at that
address. for a big endian system, you have to know a priori what the
size of the variable at the address is before you can get the lowest
let's write the 32-bit value 0xaabbccdd into memory location zero:
addy BE LE
00: aa dd
01: bb cc
02: cc bb
03: dd aa
if I want to read the lowest byte (dd) on a little endian system, I
always know it's at address zero, no matter if the variable happens to
be a 8, 16, 32, or 64 bits. for a big endian system, the location of
that lowest byte changes depending on whether the variable is 8, 16, 32,
or 64 bits.
whether or not it's useful is debatable. :)
Aaron J. Grier | "Not your ordinary poofy goof." | firstname.lastname@example.org
"It's not fast, but why not?" -- John Klos on VAX dnet client
"because it needlessly contributes to global warming?" -- Paul Vixie