Page "MMX (instruction set)" Paragraph 13

SSE2, introduced with the Pentium 4, further extended the x86 SIMD instruction set with integer ( 8 / 16 / 32 bit ) and double-precision floating-point data support for the XMM register file.

SSE2 also allowed the MMX opcodes to use XMM register operands, but ended this support with SSE4 ( and recently with SSE4. 2, introduced in the Core microarchitecture.

) However, since processor support for any SSE revision also implies support for MMX, the removal does not limit the types of data types usable by x86 SIMD.