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The AltiVec Information Source

A New Definition of Performance - AltiVec Technology
By Kalpesh Gala, AltiVec Technology Product Manager, Motorola

AltiWho? AltiWhat? AltiVec! So what is this AltiVec thing? AltiVec is Motorola's high-performance vector parallel processing expansion to the PowerPC architecture. 

The new AltiVec technology expands the capabilities of PowerPC microprocessors by providing leading-edge, general-purpose processing performance while concurrently addressing high-bandwidth data processing and algorithmic-intensive computations. Traditionally, many performance hungry applications have contained a combination of a microprocessor performing the system control function and other off-chip devices, such as a DSP farm or custom Application Specific Integrated Circuits (ASICs), handling specialized computations. AltiVec enables a new class of PowerPC microprocessors that eliminates the need for such off-chip technologies. 

What is AltiVec?

"AltiVec offers dramatic enhancements for existing PowerPC customers, and will also open new markets, making it the flagship of Motorola's processor portfolio...This chip is a butt-kicker!"

-- Will Strauss, Forward Concepts 

AltiVec is the SIMD (Single Instruction Multiple Data) extension to the PowerPC Architecture. The 128-bit vector engine, which is the heart of Motorola's AltiVec technology, is an extremely powerful and efficient execution unit that works concurrently with the existing PowerPC computing engines. This new vector engine enables highly parallel operations, allowing simultaneous execution of up to 16 operations in a single clock cycle. 

AltiVec is a short vector parallel architecture, in contrast to the long vector architectures of supercomputers that were popular in the 1980s. Vector sizes for those machines ranged to hundreds of elements. The long vector approach of supercomputers, while useful for scientific calculations, is not optimal for the communications, multimedia and other performance-driven applications targeted by Motorola with AltiVec technology. Depending on the desired data type (integer, floating point or character), AltiVec vectors are 4, 8 or 16 elements long, which directly correlates to 4-way, 8-way or 16-way parallelism. 

Applications of the AltiVec Technology

The initial target applications for PowerPC processors utilizing AltiVec technology include, but are not limited to: 

  • Desktop and embedded computing
  • Speech processing systems
  • Image and video processing systems
  • High performance digital signal processing
  • Scientific array processing systems
  • Virtual private network servers
In addition to accelerating next-generation applications, AltiVec can, through its wide datapaths and numerous operations, also accelerate many traditionally time-consuming computing and embedded processing operations. While the first PowerPC microprocessor utilizing AltiVec technology targets very high-performance applications in networking and computing, future Motorola processors with AltiVec could address markets and applications where performance must be balanced with power, price and peripheral integration. 

A New Definition of Performance

Software optimized for the 128-bit vector processor can achieve huge gains in performance. The use of high-level language extensions allows developers to easily vectorize their applications, realizing average increases between 1.5 and 6 times that of today's traditional scalar applications. While these application speedups are impressive, numerous algorithms have demonstrated performance gains well in excess of 10x. 

Want to Learn More?

For more information, visit Motorola's AltiVec website at http://www.mot.com/AltiVec, and continue to navigate the  industry-wide user's forum at http://www.AltiVec.org.