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Old 24 April 2015, 02:38   #45
Join Date: Jan 2010
Location: Kansas
Posts: 1,284
Originally Posted by JimDrew View Post
I think the daughter board uses a 75MHz 060, but I guess that people don't understand that the FPGA's 020 core is much faster than the real 060 daughter board setup.
There is a video on YouTube showing MAC emulation using the daughter board with a revision 6 68060 clocked over 100MHz. Other 68060 revisions would be lucky to clock to 66MHz with most being limited to about 60MHz.

Originally Posted by robinsonb5 View Post
A mega-fast '020 is a very interesting processor but I remain to be convinced that FPU emulation won't come with a severe speed penalty - I'd love to be proved wrong though.
I expect from fastest to slowest:

1) hard FPU like 68060
2) FPGA FPU emulation
3) software floating point

Floating point for the 68k requires fast wide shifting which is slow in an FPGA. Of course speed is relative as 6888x performance should be possible in FPGA but even 68060@50MHz FPU performance would likely be difficult.

Originally Posted by robinsonb5 View Post
I remember playing with a Mac SoftFPU in ShapeShifter and being delighted to see that the emulated FPU leaked over into the Amiga side too - yet I don't think anyone created an equivalent for the Amiga, did they?
Any software FPU emulation would have been slower than:

1) IEEE math fp libraries (accelerated with FPU)
2) FFP math fp libraries (faster than IEEE but no FPU acceleration)
3) compiling with software fp

SAS/C (Lattice) allowed all 3 options above from very early and other compilers had similar options as well. FPU emulation would likely involve trapping which would be slower than all the options above.
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