IIRC later revisions of the 486SX have a unique mask set without the FPU, presumably the higher chips per wafer made up for the extra tooling costs. Also, as a

IIRC later revisions of the 486SX have a unique mask set without the FPU, presumably the higher chips per wafer made up for the extra tooling costs. Also, as a note, unlike modern chips where they fuse off broken cores and sell them as lower specs[1] as part of the binning process, with the early 486SX the FPU was disabled before any testing / binning, so they weren’t selling broken DX dice as SXs. [1] Or in some cases, fusing if working silicon if the supply / demand curve works that way, see the infamous 3 core AMD Phenom.