MIPS-X is a microprocessor and instruction set architecture developed as a follow-on project to the MIPS architecture at Stanford University by the same team that developed MIPS. The project, supported by the Defense Advanced Research Projects Agency, started in 1984, and its final form was described in a set of papers released in 1986–87. Unlike its older cousin, MIPS-X was never commercialized as a workstation CPU, and has mainly been seen in embedded designs based on chips designed by Integrated Information Technology for use in digital video applications.
MIPS-X, while designed by the same team and architecturally very similar, is not instruction-set compatible with the mainline MIPS R-series processors. The processor is obscure enough that (as of November 20, 2005) support for it is provided only by specialist developers (such as Green Hills Software), and is notably missing from GCC.
MIPS-X has become important among DVD player firmware hackers, since many low-end DVD players use chips based on the IIT design[clarification needed] (and produced by ESS Technology Inc.) as their central processor and MPEG-2 decoder.
The Programmer's Manual jokingly describes an instruction called hsc, which means halt and spontaneously combust. The manual claims that on the NSA versions of the processor, this instruction is executed when a protection violation is detected. On other platforms, this type of instruction is known as Halt and Catch Fire.
- hsc instruction, MIPS-X Instruction Set and Programmer's Manual, p. 65.
- The original MIPS-X paper from Stanford.
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