FSTCW             Store Control Word            Exception Flags: None

FSTCW memory location

       Logic:      [memory location] . control word

     FSTCW stores the control word in a 16-bit memory location. The no-wait
     form of this instruction is FNSTCW. The FSTCW form checks for unmasked
     exceptions before storing the word, but FNSTCW does not.

     The control word stores all exception masks, the interrupt enable mask,
     and fields for precision control, rounding control, and infinity control.

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   Operands            Clocks         Bytes           Example
   FSTCW memory16      12-18           4              FSTCW CONTROL_WORD
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