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Introduction to AltiVec Technology:
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Expanding Capabilities

Motorola's 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 in a single-chip solution.

Traditionally, many high-performance systems contain a combination of a microprocessor and additional off-chip devices based on one or more other architectures.

The microprocessor performs system control function and general processing computations

These off-chip devices, such as a DSP farm or custom ASICs, perform specialized computations.

AltiVec technology will enable a new class of processors that provide for the convergence of these capabilities. AltiVec technology provides embedded and computing system designers with a new "one part–one code base" approach to product design. Because this integrated solution is still 100 percent compatible with the industry standard PowerPC Architecture, design and support are simplified and the development barriers inherent to older multiple architecture designs are eliminated. System designers, and their customers, will benefit through the reduced time-to-market and lowered total system development expense, while simultaneously enjoying a tremendous jump in performance.

Key Elements

Key elements of Motorola's AltiVec technology include:
  • 128-bit vector execution unit
  • Vector permute unit
  • Parallel processing
  • 162 new instructions

Vector Execution Unit

128-bit Vector Execution Unit

The heart of Motorola's AltiVec technology is an extremely powerful and efficient vector execution unit which works in conjunction with the PowerPC Architecture's existing computing engines, the floating point and integer units.

This new vector execution engine processes data 128 bits at a time in 32 additional 128-bit-wide registers. Registers are storage units within microprocessors that hold bits of data while they're being processed; thus, microprocessors with wider registers can hold and manipulate more data at once. AltiVec technology expands the PowerPC Architecture's register banks to an unequaled width of 128 bits — that's at least twice as wide as any other mainstream microprocessor, which generally process data in 32- or 64-bit increments at a time. This means that a PowerPC processor with AltiVec technology will process a standard 1,024-bit piece of data in one-fourth the time of a microprocessor with 32-bit registers.

Parallel Processing

The new vector execution unit employs a parallel processing model known as Single-Instruction Multiple-Data, or SIMD (sim-DEE). In SIMD parallel processing, a central unit fetches and interprets instructions and then executes the instructions by using not just a single piece of data, but by processing up to 16 pieces of data simultaneously. Unlike conventional processors, in which instructions work on individual bits of data in sequence, SIMD processors work on whole streams of data at once, making it a highly efficient, fast way to manipulate large quantities of information.

162 New Instructions & Vector Permute Unit

To take full advantage of AltiVec technology's parallel processing and its 128-bit registers, Motorola added 162 new instructions to accelerate computations. Among the most notable new features is a vector permute function capable of completely rearranging data in the registers. This capability is extraordinarily useful when converting data from one format into another. Such conversions are often necessary in voice, video and graphics applications, which require data to be preserved in a variety of specific formats.

For example, the video coming off the new high resolution DVD video discs is stored in a format called MPEG-2. In order to display this video on a screen the digital data that makes up the images stored on the DVD disc must be rearranged into a very specific order. AltiVec technology can reorganize this data at over 30 times the speed of a traditional microprocessor.

Applications of AltiVec Technology

Motorola's AltiVec technology works synergistically with the existing PowerPC Architecture to greatly accelerate data-intensive computations required for next-generation communications infrastructure, video, audio and graphics applications. Such applications require the repetitive execution of a sequence of instructions (or loops) on huge volumes of data. With AltiVec technology, operations that once required several loops can now be performed in one.

The initial target applications for PowerPC processors utilizing AltiVec technology include:

  • IP telephony gateways
  • Multi-channel modems,
  • Speech processing systems
  • Echo cancelers
  • Image and video processing systems
  • Scientific array processing systems
  • Internet routers
  • Virtual private network servers

The Origin of New Possibilities

Upcoming microprocessors incorporating AltiVec technology will be able to complete up to 16 operations at a time. Such performance is unrivaled among existing microprocessor architectures. Ultra-high performance systems that currently require multiple processors or dual-core devices will soon be able to use single-chip solutions from Motorola.

Products based on Motorola’s AltiVec technology will not only reduce component count, form factors and power consumption in many of today’s high-end embedded systems, it will also likely change the industry’s definition of microprocessors.