Jack Jansen :

with even SP and PC being general purpose registers

The PC is not a general purpose register in the 68000. I've heard that this was because DEC had a patent on the idea.

the latter two actually improved on the PDP-11

The 16032 was certainly extremely orthogonal. I wrote an assembler and a compiler for it once, and it was a joy after coming from the Z80! It wasn't quite perfect, though - its lack of a "top-of-stack-indirect" addressing mode was responsible for the one wart in my otherwise-beautiful code generation strategy. Also, it must have been the most CISCy instruction set the world has ever seen, with the possible exception of the VAX... Greg Ewing, Computer Science Dept, +--------------------------------------+ University of Canterbury, | A citizen of NewZealandCorp, a | Christchurch, New Zealand | wholly-owned subsidiary of USA Inc. | greg@cosc.canterbury.ac.nz +--------------------------------------+