Very soon now, you'll have a choice of three different 64-bit architectures
for your desktop computer. The AMD Athlon 64 processor will be available
in systems running Linux and Windows, and IBM's PowerPC 970 will
ship in Apple's new Power Mac G5. The third option is perhaps the
least well known, though it's been available for some time—Sun's
UltraSparc III, shipping in Sun Blade 150 workstations priced as
low as $1,395.
Some of these segment associations are a little vague. The Sun
Blade 150 is a workstation in name only, having low-performance
processor, graphics, and mass-storage components. The G5 is a workstation
masquerading as a desktop, offering premium features at a premium
price. AMD would probably prefer that its workstation OEMs use Opteron
chips, but Athlon 64 will be widely used in both desktop- and workstation-class
systems.
Whatever you call it, a 64-bit desktop has capabilities not found
in commodity 32-bit machines. Though we've long had desktops with
performance to match the best supercomputers of a decade ago, we
haven't been able to run the same software on them. Huge databases
and complex scientific simulations can now be hosted on inexpensive
machines that support 64-bit addressing in both hardware and software.
These sophisticated programs, however, probably won't create much
end-user demand for 64-bit systems. Most of us will continue to
visit www.weather.com
rather than attempting to predict tomorrow's weather ourselves.
Similarly, we'll continue to use conventional client-server database
programs rather than hosting billion-record databases directly on
our desktops. Over time, some of these applications may migrate
to the desktop, but with new purposes. Programs created to help
NASA scientists visualize the surface of Mars will turn into 3D
games, and, as hard disks get bigger and bigger, 64-bit database
engines will be used to manage our local file systems.
Unfortunately, this migration won't be fast enough to help AMD,
IBM, and Sun sell their desktop processors this year—or next.
Some customers will be savvy enough to realize that if they expect
to be running 64-bit desktop software in 2005, they should start
buying 64-bit systems now, but that's a tough sell for most customers.
Until 64-bit software is widely available, price and performance
will continue to be the most important selling points.
Accordingly, we can expect to see 64-bit computing presented as
a performance advantage with immediate relevance. In some small
ways, it is. The ability of these 64-bit platforms to support large
amounts of DRAM can speed up memory-hungry programs, and the larger
register sets associated with 64-bit CPUs can improve performance
on recompiled 32-bit applications—but these are not very dramatic
effects. Most performance benefits related to 64-bit processing
have already been realized in 32-bit systems by means of instruction-set
extensions such as Intel's SSE, AMD's 3DNow!, IBM/Motorola's AltiVec,
and Sun's pioneering VIS.
All these extensions implemented 64-bit (or wider) datapaths and
register sets for special-purpose instructions. AMD and Apple, in
particular, will find ways for general-purpose code to benefit from
64-bit processing, but these benefits will, at best, be incremental
over the capabilities of 3DNow! and AltiVec.
If 64-bit addressing is of little immediate importance, and 64-bit
processing offers only a slight performance advantage, what will
AMD and Apple use to sell their new hardware? Both companies have
a simple, strong performance argument, but it has nothing to do
with 64-bit capabilities. This argument will certainly be the centerpiece
of the Athlon 64 and G5 marketing efforts, but both companies are
clearly compelled to do something with their 64-bit story, however
weak it is.
There's an old lawyer joke: When the law is on your side, plead
the law. When the facts are on your side, plead the facts. When
neither the facts nor the law are on your side, plead loudly. We
can expect to hear some loud pleading in the months to come.
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