MMX is a single instruction, multiple data (SIMD) instruction set designed by Intel, introduced in 1997 with their P5-based Pentium line of microprocessors, designated as "Pentium with MMX Technology". It developed out of a similar unit introduced on the Intel i860, and earlier the Intel i750 video pixel processor. MMX is a processor supplementary capability that is supported on recent IA-32 processors by Intel and other vendors.
MMX has subsequently been extended by several programs by Intel and others: 3DNow! and ongoing revisions of Streaming SIMD Extensions.
Naming
MMX is officially...