Motorola 68881

The Motorola 68881 math coprocessor is a floating-point unit (FPU) that was produced by Motorola's Semiconductor Products Sector for use with the Motorola 68020 processor.

The 68020 can manage up to 8 coprocessors, though no 68k-based Macintosh ever shipped with more than one math coprocessor. The only model to ship with a 68881 pre-installed was the Macintosh II.

The 68881 was succeeded by the Motorola 68882 math coprocessor, which was designed for the 68030 processor with improved pipelining. The 68881 and 68882 are actually interchangeable between the 68020 and 68030, with 10% performance improvement observed in the 68882.