FCHS
Usage: FCHS Modifies flags: None
Complements the sign bit of ST(0). Changes a positive value into a negative value of equal magnitude or vice versa.
Floating-Point Change Sign
FCHS ; D9 E0 [8086,FPU]
FCHS negates the number in ST0, by inverting the sign bit: negative numbers become positive, and vice versa.
EXAMPLE:
fchs