FCOM              Compare Real                Exception Flags: I D

FCOM [source]

       Logic:      CMP ST, source
                   sets condition codes in the status word:

                   C3 C2 C1 C0    Means
                   -- -- -- --    -----------
                   0  0  ?  0     ST > source
                   0  0  ?  1     ST < source
                   1  0  ?  0     ST = source
                   1  1  ?  1     ST not comparable to source

     FCOM compares a real number to ST and leaves the result encoded in the
     status word as shown above. If no source is specified, ST(1) is
     compared to ST. Otherwise, source is compared to ST.

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   Operands            Clocks         Bytes           Example
   FCOM reg            40-50            3             FCOM
   FCOM MEMORY_REAL    60-75+EA         5             FCOM REAL_NUMBER
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