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Learn Something Old Every Day, Part XVIII: How Does FPU Detection Work?

66 points by kencausey

by userbinator

2 subcomments

Speaking of recent x86 processors with an FPU, it's notable that some variants of the https://en.wikipedia.org/wiki/Intel_Quark were basically a 486SX core with some Pentium instructions "backported", and hence lack the FPU.
Of course there's also the https://en.wikipedia.org/wiki/Vortex86#Vortex86SX , an interesting legacy from an era when there was far more competition in x86-compatible CPUs.

by scorpionfeet

1 subcomments

One small nit:
“it cannot have an FPU added (that is not the case with Cyrix 486S…)”
This is mostly true but the 486SX can be paired with a math coprocessor via the 487SX, but the 487SX is actually a full CPU that disables the SX, not a full FPU!