Extended MMX

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Extended MMX, also known as EMMI (Extended Multi-Media Instructions), was an instruction set developed by Cyrix and implemented on their 6x86 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 SSE instructions even share opcodes with EMMI instructions). It was never implemented in any processors after the MII. [1] The EMMI instruction set included:

  • paddsiw
  • paveb
  • pdistib
  • pmachriw
  • pmagw
  • pmulhrw
  • pmulhriw
  • pmvzb
  • pmvnzb
  • pmvlzb
  • pmvgezb
  • psubsiw


  1. ^ Wright, Christopher (January 2004). "AMD MMX Extensions". AMD MMX Extensions. Retrieved 23 March 2013.