68060ec vs 68030

[Iggy]

What prevents a 68060 w.o an MMU or FPU from running 68030 code?

[Karlos]

What prevents a 68060 w.o an MMU or FPU from running 68030 code?

Nothing, provided you have the necessary exception handlers installed to emulate the missing integer instructions (32x32->64 bit multiply, bitfields and so on).

[freqmax]

And that you don't require any memory protection support. Exception handler for MMU is quite harder.

In essence the code can run provided that it won't use any of the missing functionality.

[Karlos]

And that you don't require any memory protection support. Exception handler for MMU is quite harder.

In essence the code can run provided that it won't use any of the missing functionality.

True, but I assumed (perhaps falsely) that this was a given.

[matthey]

Nothing, provided you have the necessary exception handlers installed to emulate the missing integer instructions (32x32->64 bit multiply, bitfields and so on).

The 68060 has the bit field instructions. 64 bit integer multiplication and division are missing though. 68020/68030 code is fairly optimal on the 68060 except for branch logic being reversed and the 68060 branch cache will mostly solve that. The larger caches, dual integer units and faster instructions would mean the 68060 could run 68030 code significantly faster (68030@100MHz speed?). The larger caches could cause problems with poorly written code.

[Karlos]

Hmm, perhaps it was something else I was thinking of?