A.5.86 FINIT, FNINIT: initialize Floating-Point Unit
FINIT ; 9B DB E3 [8086,FPU]
FNINIT ; DB E3 [8086,FPU]
FINIT initializes the FPU to its default state. It flags all registers
as empty, without actually change their values, clears the top of
stack pointer. FNINIT does the same, without first waiting for pending
exceptions to clear.