@Snial : it's likely fairly heavily 68k. It's probably also more 601 compatible than 604 compatible as early PPC work was done with an IBM compilers that spat out POWER code instead of pure PowerPC, meaning there were a few unsupported opcodes sprinkled in there.
@Snial
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The 601 supported both instruction sets, but the 604 only supported PowerPC. The nanokernel emulates some POWER ops on PowerPC to maintain compatibility.
"IBM compilers that spat out POWER code " there's quite a bit of that in the Gary Davidian oral history. His work on the 68K emulator is epic. I especially liked the part where his first version was designed for the Motorola 88000 and hacked onto an LC! I mean, if you're going to write a ground-breaking 68K emulator, you're gonna use the cheapest colour Mac at the time huh?