FSUBP             Subtract Real and Pop       Exception Flags: I D O U P

FSUBP destination, source

       Logic:      ST(i) . ST(i) - ST
                   pop stack

     FSUBP subtracts two operands. It takes the source operand from ST,
     and the destination operand must be part of the stack, ST(i). It
     performs the operation, puts the result in the indicated ST(i) register,
     and then pops the stack.

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   Operands            Clocks         Bytes           Example
   FSUBP reg, reg      75-105           3             FSUBP ST(1), ST
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