with an extra pin, for use in the
coprocessor socket of an
missing in the 486SX.
Although the 486SX is completely disabled when you install a
487SX, the 487SX design requires that you leave the 486SX in
your PC [why?], rather than use it elsewhere. Intel admits
that in some systems you can unplug the 486SX and fit a 487SX
in its place but they don't guarantee that it will always
work.
(1995-05-10)