A.5.102 FST, FSTP: Floating-Point Store
FST mem32 ; D9 /2 [8086,FPU]
FST mem64 ; DD /2 [8086,FPU]
FST fpureg ; DD D0+r [8086,FPU]
FSTP mem32 ; D9 /3 [8086,FPU]
FSTP mem64 ; DD /3 [8086,FPU]
FSTP mem80 ; DB /7 [8086,FPU]
FSTP fpureg ; DD D8+r [8086,FPU]
FST stores the value in ST0 into the given memory location or other FPU
register. FSTP does the same, but then pops the register stack.