January 25, 1999
Pentium III learns something new from the past
By Bob O'Donnell
Innovation in the computer industry -- more often than not -- comes from evolution of
existing products. The Rev 2, Version III, or annual year number model of today's hardware
and software often offers the special feature(s) or capability(ies) that motivates people
to finally purchase the product they've been considering.
Not surprisingly, then, Intel's next-generation of processors, the Pentium III line --
which is due to be launched a little over one month from now -- builds on the capabilities
of the previous line. In fact, based on the information currently available on the
product, the Pentium III bears a striking physical and structural resemblance to the
Pentium II, though it does have some nifty tricks up its sleeve.
Physically, the Pentium III is supposed to look identical to the Pentium II -- except
for the new logo sticker, of course. It's in the same Single Edge Cartridge Connector
(SECC) packaging and it fits into the same 242-pin connector that Intel's Web site now
says was "formerly known as Slot 1." (As an aside, there are apparently two
slightly different SECC "packages," both for existing Pentium IIs, as well as
Pentium IIIs. The SECC-2 packaging uses a more universal post connector which can connect
with both Pentium II and III cartridges, as well as cartridge-less Celeron processor
cards. You can put an SECC-2 cartridge into an original SECC slot, and vice versa, but the
two types of cartridges fit more snugly into their matching connectors.)
Structurally, the chip is also very similar to its predecessor, with one important
difference. Like the Pentium II, Pentium III features 512K of onboard Level 2 cache that
connects to the processor at one half the speed of the processor core. Unlike the new
mobile Pentium IIs introduced this week (codenamed Dixon) -- which, like current Celerons,
incorporate Level 2 cache into the processor core itself -- Pentium III's Level 2 is still
separate -- at least, in the initial versions. Later generations are supposed to
incorporate Level 2 cache into the processor core, with the benefit that it will run at
the full speed of the processor. In addition, the company plans to build later Pentium
IIIs with .18 micron technology, versus the .25 micron wafer size of today, which should
allow them to crank up speeds and lower costs.
The big difference between Pentium II and III is the addition of the new Streaming SIMD
instructions (formerly known as Katmai New Instructions), a set of 70 new processor
instructions designed to improve the processor's floating point performance. This, in
turn, should lead to improvements in the performance and capabilities of existing
applications -- particularly things like games, voice recognition, audio, video and image
editing, and more. Another difference is that the Pentium III is the first Intel processor
to include a unique serial number embedded into the chip. The company hopes that, with
additional software support, this can bring added security to things like online
transactions.
Interestingly, even Streaming SIMD (Single Instruction, Multiple Data -- a processing
technique for performing the same operation on multiple chunks of data simultaneously)
builds on the technology of its predecessor -- in this case, the 57 processor instructions
that were introduced into the x86 architecture a little over two years ago in MMX. MMX
also uses SIMD, but whereas MMX did SIMD on integer data, Streaming SIMD does SIMD on
floating-point data. Streaming SIMD also incorporates support a technology Intel calls
Streaming Memory, which lets applications get to data in memory more efficiently, though
it may take the introduction of support for Rambus memory before this can be taken
advantage of.
As with MMX, the problem with Streaming SIMD is that it doesn't do any good unless
applications are written, or updated, to specifically support the new instructions. Even
now, very few applications are available that use MMX, which means you could arguably call
it a flop. Intel seems to be keenly aware of this and is trying to learn from its mistakes
by priming the pump for Streaming SIMD-supported applications. In fact, one big win for
Streaming SIMD is that the next version of DirectX -- which Microsoft's Web site says will
be 6.1 -- will include support for Streaming SIMD instructions. As a result, any game or
other app that uses DirectX 6.1 will benefit from Streaming SIMD. (Of course, DirectX 6.0
added support for Advanced Micro Devices' competitive 3DNow instruction set, found in its
K6-2 line of processors.)
One other area where the Pentium III is, unfortunately, similar to its predecessor is
that it's not being launched with a new chipset that can best exploit all its features. As
with Pentium II, there will be a several-month lag between the introduction of the
processor and the introduction of a new chipset, in this case the rumored 820. On the one
hand, introducing Pentium III with existing chipsets allows for upgrades and backward
compatibility. Plus it makes it easier for OEMs to crank out new systems. But, for power
users who want an entirely upgraded platform, they'll have to wait for the 820, just as
Pentium II users had to wait for the 440LX.
While it's still early to say for sure, Pentium III should be a nice incremental
improvement over Pentium II, as long as Intel can line up a critical mass of application
support for Streaming SIMD (and vendors don't charge too much for upgrades). I, for one,
am looking forward to checking one out.
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Copyright 1999, by InfoWorld Publishing Corp., a
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