AltiVec MACS execute multimedia instructions........
Apple's ties Mac's future to AltiVec instructions
By Craig Matsumoto
SAN JOSE, Calif. - Apple Computer Inc. will use the AltiVec instruction
set in Macintosh computers and expects to have AltiVec-enabled Macs for
sale in the first half of next year, the company said at its Worldwide
Developers Conference yesterday.
It it still unclear what effect these plans will have on Apple's relationship
with IBM Corp., which will continue to develop PowerPC processors
without AltiVec. Apple officials made it clear that AltiVec is a big part of
the Macintosh's future - the Mac OS is even being altered to exploit the
instructions.
Speaking at the conference's hardware keynote yesterday, senior vice
president of hardware engineering Jon Rubinstein said Apple had spent
two years assisting Motorola Inc. in developing AltiVec, which consists of
162 new PowerPC instructions that target multimedia applications and are
optimized for MacOS native code.
"This is not some tacky little add-on to the chip," said Keith Diefendorff,
director of processing architecture for Apple and the company's chief
AltiVec architect. "This is a significant investment in transistors."
Company officials spoke to a largely supportive crowd at the conference.
Many of the developers attending Diefendorff's session on the PowerPC's
future developments were anxious to get their hands on development tools
for AltiVec, and Diefendorff drew strong murmurs of approval when he
hinted at some of the functionality that AltiVec could make possible, such
as a software-based cellular phone inside a laptop computer.
Initially dubbed "VMX," for "vector multimedia extension," AltiVec adds
an independent vector unit aside from the integer and floating-point units
within a chip to provide a faster and wider path for multimedia-driven
calculations. The vector unit has 32 registers of 128 bits each, and a
dedicated 128-bit pipeline to memory, which is wider than the 64 bits that
are available to the floating-point unit.
Apple hopes AltiVec goes beyond its multimedia roots and provides a
speed boost to any algorithm that can take advantage of parallel
processing. Apple has already tried this with several algorithms, and
Diefendorff encouraged developers to do the same.
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