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Floating point hardware was optional for a long time. 486 in 1989 was first Windows PC CPU with floating point standard. Before that it was an add on co-processor for the 386. New 386 models were coming out until 1992, so it took a long time before you could count on floating point support being there.

There are still a lot of embedded microprocessors without floating point support.

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Even the relatively expensive Motorola 68k chips didn't have built-in floating point until the 68040 in 1990.

I'd forgotten it was that early. The Sun box on my desk was a 68020 with a 68881. Everything having to do w/ FP, certainly on our DSPs (which is silly), we had to implement a knock-off of IEEE 754 in software ourselves.

The 486sx was also in the mix for some time after that.

Which had the amusing feature that some motherboards let you add a '487 FPU' [0], which was actually a 486DX that took over completely from the SX.

[0] https://en.wikipedia.org/wiki/X87#80487

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