The Intel ‘486 had the FP coprocessor integrated, but they split the line into the DX and SX models. The only difference was that the SX had the FP unit physically disabled.
They still sold a 80487, of course. It was a '486 without the FPU being fused off, and when you plugged it into the "math co-processor" socket, it disabled the original CPU and took over both duties.
