We'll have
to agree to disagree on that. MC68020 is the first 32
bit CPU in the 68K line.
How does one define 32 bit cpu? I know nothing about the
68020 but I
am guessing a 32 bit bus, and some sort of virtual memory.
Well, for one thing, the programmer-visible registers are (almost?) all
32 bits wide. 32 bits is the size most operations (add, subtract,
shift, etc) operate on. That makes it a 32-bit architecture to me,
regardless of what kind of bus it has - even if it were bit-serial,
those attributes would make it a 32-bit machine to me.
Virtual memory is not, to my mind, either necessary or sufficient for a
machine to be a 32-bitter. Indeed, IIRC the 68020 does not have any
kind of MMU; when present, that's separate (common, but separate and
not necessary). I think the '040 was the first 68k-series CPU to have
an on-chip MMU (and if I'm wrong I'm sure someone will correct me!).
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