Alternate Instruction Set

The Alternate Instruction Set (AIS) is a second 32-bit instruction set architecture found in some x86 CPUs made by VIA Technologies. On these VIA C3 processors, the second hidden processor mode is accessed by executing the x86 instruction JMPAI (0F 3F).[1] If AIS mode has been enabled, the processor will perform a JMP EAX[2] and begin executing AIS instructions at the address of the EAX register. Using AIS allows native access to the Centaur Technology-designed RISC core inside the processor.[3]

  1. ^ Cite error: The named reference ais_appnote was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference via-200211 was invoked but never defined (see the help page).
  3. ^ Stiller, Andreas (2003-01-22). "VIAs Prozessor der siebten Generation" [VIA's seventh-generation processor]. Heise Online (in German). Heinz Heise. Retrieved 2018-08-12. Als … kann man Nehemiahs RISC-artigen Core auch native programmieren (AIS: Alternate Instruction Set). Auch hier wird sich zeigen, ob findige Programmierer das für den einen oder anderen Treiber nutzen können, um hier mehr Performance herauszukitzeln.