johnf@light.ssl.berkeley.edu (09/17/88)
A naive question: A friend and I were looking at the section of the 68010 manual which discusses virtual memory support on that chip, and it looks not too difficult (well...). Basically, it looks as though one simply has to put the address of a swapper routine in address $08. When the '010 gets a bus error from trying to address non-existing memory, it pushes everything onto the supervisor stack and does a jump to whatever is pointed to in $08. The swapper would bring in the needed page from disk, and RTE back to let the '010 continue. I don't know much about such things, but it seems as though it should be possible to write some VM handler to enlarge the address space. I guess the fact that nobody has done it yet is an indication that it is not trivial. I suppose that the memory allocation stuff in the os would need to be modified. Does anybody who knows about this kind of stuff care to comment? Am I completely misguided? As a side question, why doesn't Commodore ship Amigas with 68010's in them instead of 68000's? They would only add about $10-$15 in cost, and while the performance gain would not be remarkable the image would be improved. When I hear 68010, I think 'sun2'. When I hear 68000, I think 'macintosh'. '68010' just plain sounds better than '68000', and would make the machine stand out better. Just thinking... --john flanagan johnf@sag4.ssl.berkeley.edu