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Mac OS 8

The PowerFPU control panel on Mac OS 8.1

PowerFPU is a control panel for classic Mac OS from John Neil & Associates that redirected floating-point instructions from vintage 68k software to the PowerPC processor when run in emulation.


John Neil & Associates' previous product, SoftwareFPU, found use when Apple begin its transition from 68k to PowerPC processors. Though PowerPC processors contained floating-point hardware, the 68k emulator in classic Mac OS only emulated a 68LC040 without floating-point hardware, causing old 68k software that did not perform necessary hardware checks to fail. Though SoftwareFPU 3.0 was available as a fat binary, running floating-point emulation with emulated 68k software was still very slow.[1]

John Neil & Associates then licensed PowerFPU from Todd Pittman, which would directly route such instructions to the appropriate PowerPC-native instructions, enabling performance improvements that was over 10 times faster than SoftwareFPU and approached the speed of Motorola 68881 / 68882 co-processors. PowerFPU was written in a combination of PowerPC assembly language with other routines compiled with CompileIt![2]


  1. SoftwareFPU: Programmer Information (PDF), by John Neil & Associates, Todd Pittman. 1999-01-30.
  2. PowerFPU by Tom Pittman, Itty Bitty Computers. 2007-10-08.

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