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"
MMX is a trademark used to reference an extension to the Intel Architecture Instruction set. Officially Intel states the initials are meaningless. This extension adds 57 opcodes, a 64-bit quadword datatype and eight 64-bit registers. These registers can be addressed using the names mm0 through mm7.
To avoid compatibility problems with the context switch mechanisms in existing operating systems, these registers were aliases for the existing x87 FPU stack registers. Unlike the FP stack, the MMn registers are directly addressable.
The main usage of the MMX instruction set is based on the concept of packed data types, which means that instead of using the whole register for a single 64-bit integer, two 32-bit integers, four 16-bit integers, or eight 8-bit integers may be processed concurrently. Thus, the unofficial initials are known as "MultiMedia eXtension" or "Matrix Math eXtension."
The mapping of the MMX registers onto the existing FPU registers made it somewhat difficult to work with floating point and SIMD data in the same application.
MMX provides only integer operations
