[_chris_]

If you want to do some further archeology, check out the SMIPS ISA, which I believe dates back to 2005 (which itself gradually evolved from the T0/Scale/6.371 MIPS ISAs; and the earliest, T0, was derived from MIPS-II).

[brucehoult]

Seems to be just exactly MIPS-II, down to the encoding, but with stuff left out.

http://csg.csail.mit.edu/6.S078/6_S078_2012_www/handouts/smi...