<processor> An Intel 486DX microprocessor with its floating-point unit disabled.
Presumably all 486SX chips are fabricated with FPUs and then tested to see if it works. Those with broken FPUs are sold cheaper as SX, those with working FPUs as DX.
[Is this true of all 486SX chips?]
The German computer magazine, "c't", once made this the basis of an April Fools Joke. They claimed that the SX was in fact crippleware, and if one drilled a hole of a specified diameter through the right point on a SX chip, this would brake the circuit that disables the FPU. Some people actually tried (and then bought themselves new processors).
(01 Sep 1996)