Extended MMX refers to one of two possible extensions to the MMX instruction set for

x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introd ...

Intel Extended MMX

Included in Intel's

Streaming SIMD Extensions In computing, Streaming SIMD Extensions (SSE) is a single instruction, multiple data (SIMD) instruction set extension to the x86 architecture, designed by Intel and introduced in 1999 in their Pentium III series of Central processing units (CPUs) ...

were a number of new instructions that extended the functionality of MMX. AMD incorporated this subset of extended MMX instructions into the

Athlon Athlon is the brand name applied to a series of x86-compatible microprocessors designed and manufactured by Advanced Micro Devices (AMD). The original Athlon (now called Athlon Classic) was the first seventh-generation x86 processor and the fi ...

microarchitecture. These instructions are commonly known as "Extended MMX instructions". These instructions debuted in May 1999, in the Intel

Pentium III The Pentium III (marketed as Intel Pentium III Processor, informally PIII or P3) brand refers to Intel's 32-bit x86 desktop and mobile CPUs based on the sixth-generation P6 microarchitecture introduced on February 28, 1999. The brand's initial p ...

Processor, as part of the SSE instruction set. Next month, in late June 1999, AMD's

processor was released which featured the extended MMX instructions, but not SSE. Today, these extended MMX instructions are notable as being the common subset of MMX extensions that work across both AMD Athlon and SSE-capable Intel processors.{{cite journal, last=Wfirst=Christopher, title=AMD MMX Extensions, journal=AMD MMX Extensions, date=January 2004, url=http://softpixel.com/~cwright/programming/simd/mmxext.php, accessdate=23 March 2013

Cyrix EMMI (Extended Multi-Media Instructions)

Less commonly known, "Extended MMX" could also refer to the original Cyrix EMMI (Extended Multi-Media Instructions). This instruction set was developed by

Cyrix Cyrix Corporation was a microprocessor developer that was founded in 1988 in Richardson, Texas, as a specialist supplier of floating point units for 286 and 386 microprocessors. The company was founded by Tom Brightman and Jerry Rogers. In 19 ...

and implemented on their

6x86 The Cyrix 6x86 is a line of sixth-generation, 32-bit x86 microprocessors designed and released by Cyrix in 1995. Cyrix, being a fabless company, had the chips manufactured by IBM and SGS-Thomson. The 6x86 was made as a direct competitor to Int ...

MX and MII line of processors. It extended the MMX instruction set with 12 new instructions useful in multimedia applications. The extensions were not enabled by default, requiring the BIOS or software to enable them. EMMI was never given much support from software developers or acknowledged by Cyrix's competitors (certain

Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...

SSE instructions even share opcodes with EMMI instructions). It was never implemented in any processors after the MII. The EMMI instruction set included: *paddsiw *paveb *pdistib *pmachriw *pmagw *pmulhrw *pmulhriw *pmvzb *pmvnzb *pmvlzb *pmvgezb *psubsiw

References

X86 instructions