A.5.76 FxDISI, FxENI: Disable and Enable Floating-Point Interrupts
FDISI ; 9B DB E1 [8086,FPU]
FNDISI ; DB E1 [8086,FPU]
FENI ; 9B DB E0 [8086,FPU]
FNENI ; DB E0 [8086,FPU]
FDISI and FENI disable and enable floating-point interrupts. These
instructions are only meaningful on original 8087 processors: the 287
and above treat them as no-operation instructions.
FNDISI and FNENI do the same thing as FDISI and FENI respectively, but
without waiting for the floating-point processor to finish what it was
doing first.