English Amiga Board - View Single Post - Is it better to use 68060 under emulation, rather than 68040?

Toni Wilen · 07 July 2018, 10:57

When using emulation 68020/030 or 68040 are the most common options. 68040 may be needed if program uses MOVE16 (=crashes without 68040). 68020/030 are easy and simple, no need for CPU libraries. There is no need for 68060 in normal use. (Use software to fake 68060 bit if some annoying program complains that it needs 68060. Should be available from aminet.)

If you need MMU, always use 68040 or 68060 if possible, 68030 MMU emulation is much slower.

Note that default CPU/FPU configuration creates super FPU that implements all existing FPU instructions. Which means you don't necessarily need to enable 68040 to get double/single FPU instruction variants (FDMOVE etc) that are not implemented in 6888x and software emulation is not needed for 68040+ missing FPU instructions.

Of course if you untick "unimplemented" checkboxes, you get exact matching CPU/FPU without extra instructions and correct exceptions when missing instruction is executed (Note that this is not JIT compatible).

There should not be nothing wrong with MOVEP exception, it probably is some other environment/config difference.

07 July 2018, 10:57	#10
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,518	When using emulation 68020/030 or 68040 are the most common options. 68040 may be needed if program uses MOVE16 (=crashes without 68040). 68020/030 are easy and simple, no need for CPU libraries. There is no need for 68060 in normal use. (Use software to fake 68060 bit if some annoying program complains that it needs 68060. Should be available from aminet.) If you need MMU, always use 68040 or 68060 if possible, 68030 MMU emulation is much slower. Note that default CPU/FPU configuration creates super FPU that implements all existing FPU instructions. Which means you don't necessarily need to enable 68040 to get double/single FPU instruction variants (FDMOVE etc) that are not implemented in 6888x and software emulation is not needed for 68040+ missing FPU instructions. Of course if you untick "unimplemented" checkboxes, you get exact matching CPU/FPU without extra instructions and correct exceptions when missing instruction is executed (Note that this is not JIT compatible). There should not be nothing wrong with MOVEP exception, it probably is some other environment/config difference.