Intel i486 DX33
Exactly the same as the SX33 execpt for the integrated co-processor. This co-processor is used for floating point calculations. At the time normal applications didn't use the FPU (floating point unit) so people had enough power with only the, much cheaper, SX 33MHz processor. After all Doom ran just as good on a SX as on a DX; Doom didn't use the FPU.

