A.5.97 FSAVE, FRSTOR: Save/Restore Floating-Point State
FSAVE mem ; 9B DD /6 [8086,FPU]
FNSAVE mem ; DD /6 [8086,FPU]
FRSTOR mem ; DD /4 [8086,FPU]
FSAVE saves the entire floating-point unit state, including all the
information saved by FSTENV (section A.5.104) plus the contents of all
the registers, to a 94 or 108 byte area of memory (depending on the CPU
mode). FRSTOR restores the floating-point state from the same area of
memory.
FNSAVE does the same as FSAVE, without first waiting for pending
floating-point exceptions to clear.