[epcoa]

Yes absolutely right about the modern RISC archs. I should have just said AT&T not AT&T/GNU. The difference is that x86, VAX and SPARC were AT&T UNIX porting efforts prior to or alongside GNU, and GNU sort of chose to inherit that. The newer RISC architectures did not have the hand/influence of AT&T as far as I know.

As far as the operand ordering with the x86, the thing is they did flip it from the Intel syntax and the beginnings of this port date back to Version 7 (1978), a few years before GNU. So what was the reason other than it looked like the incumbent/precedent PDP-11? I haven't heard it being much more than circumstance.