The history of vector programming on POWER processors begins with the AIM (Apple, IBM, Motorola) alliance in the 1990s. The AIM partners developed the Power Vector Media Extension (VMX) to accelerate multimedia applications, particularly image processing. VMX is the name still used by IBM for this instruction set. Freescale (formerly Motorola) used the trademark "AltiVec," while Apple at one time called it "Velocity Engine." While VMX remains the most official name, the term AltiVec is still in common use today. Freescale's AltiVec Technology Programming Interface Manual (the "AltiVec PIM") is still available online for reference (see ). The original VMX specification provided for thirty-two 128-bit vector registers (VRs). Each register can be treated as containing sixteen 8-bit character values, eight 16-bit short integer values, four 32-bit integer values, or four 32-bit single-precision floating-point values (the "VMX data types"). Furthermore, the integer data types have signed, unsigned, and boolean variants. An extensive set of arithmetic, logical, comparison, conversion, memory access, and permute class operations were specified to operate on these registers. The AltiVec PIM documents intrinsic functions to be used by programmers to access the VMX instruction set. Because similar operations are provided for all the VMX data types, the PIM provides for overloaded intrinsics that can operate on different data types. However, such function overloading is not normally acceptable in the C programming language, so compilers compliant with the AltiVec PIM (such as gcc and clang) were required to add special handling to their parsers to permit this. The PIM suggested (but did not mandate) the use of a header file, <altivec.h>, for implementations that provide AltiVec intrinsics. This is common practice for all compliant compilers today. The first chips incorporating the VMX instruction set were introduced by Freescale in 1999, and used primarly in Apple desktop computers. IBM's last desktop CPU (the PowerPC 970) also included AltiVec support, and was used in the Apple PowerMac G5. IBM initially omitted support for VMX from its server-class computers, but added support for it in the POWER6 server family. Next talk about VSX introduced for P7. Changes in registers and types.

Yes, it caused a lot of problems. See chapter on this.

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