This article is from the Miscellaneous Macintosh FAQ, by Elliotte Rusty Harold firstname.lastname@example.org with numerous contributions by others.
John Neil and Associates' $10 shareware ($20 for native PowerPC
version) extension SoftwareFPU emulates a floating point coprocessor
on an FPUless 68020 or 68030. See
This will let most (though not all) software that requires an FPU
run, albeit slowly. Software FPU does not work on 68000 Macs.
Version 3.0 will let some programs work on a 68LC040 Mac like the
Quadra 605, but due to a bug in the 68LC040 chip many programs may
crash. You'll need to test each program you use for compatibility.
SoftwareFPU is MUCH slower than a real FPU. It will not improve
performance for applications that do not absolutely require an FPU.
A faster payware version called PowerFPU is also available for
PowerMacs that need to run non-native programs that require an FPU.
Finally note that an earlier version of the same program called
"PseudoFPU" is still available at some archives. This is inferior