> If you had a 386DX then I believe you had the math copro? The 386SX did not have an FPU and needed the additional 387SX.

Neither had FPUs... Closest you can get is RapidCAD (which is really a 486DX adapted to 386 bus, IIRC it uses a 'jumper' for the 387 slot.)

For 386, the difference between SX and DX was whether it was a 16 or 32 bit data bus.

Where things can get more curious, is that some early 386 motherboards actually took a 287 instead of a 387...