PATHADC Home > Documentation > Hardware > Power Mac G4 Developer Note

     

---

Velocity Engine Acceleration

The Velocity Engine (also known as AltiVec) is the vector processing unit in the G4 microprocessor. Some system software has been modified to take advantage of the accelerated processing that the Velocity Engine makes possible. System software has also been modified to support low-level operations using the Velocity Engine.

The software areas that have been modified to take advantage of Velocity Engine acceleration are

• QuickTime: key codecs, including DV and photo JPEG

The software areas that have been added or modified for low-level Velocity Engine support are

• Nanokernel: the floating-point vector denormal handler

• Process Manager: context switching

• Block Move routines

The following vector libraries are included: vBasicOps, vectorOps, vBigNum, and vMathLib.