Hacker News Reader

I believe the 387 was an actual coprocessor; the _487_ may be what you're thinking of -- the 487SX contained a whole 486DX inside and just disabled the host processor [1].

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

I would concur: The 386sx was just 16 bit. The 387sx was for that 16 bit processor. The 486sx was no math co-processor, and the 487 was a whole 486 DX, i.e. the vacancy slot, brought to you by Intel Marketing.

Nope, as I commented above:

https://news.ycombinator.com/item?id=38275340

The 487 was the “full” replacement chip upgrade.

I still don’t know why the addition of the math coprocessor helped so much