Intel 80487 was introduced in 1991 as a math co-processor for Intel
80486SX family of processors. In fact, the 80487 was more than just a
co-processor. It was a full-fledged 80486 processor with integrated
Floating Point Unit. When installed into upgrade socket on 486 motherboards,
the 80486SX processor was disabled, and the 80487 was used for
both integer and floating-point calculations. After upgrade the original
80486SX CPU could be removed from its socket if desired.
Intel 80487 has the same performance as 80486DX CPU. The main
difference between them is the pinout.
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