FIADD           Integer add                          Exceptions: I D O P
                                                     C3 C2 C1 C0: ? ? ? ?
FIADD source

        Logic   ST ← ST + source

    FIADD adds a (word or short integer) memory operand to ST and leaves
    the result in the stack top.


    Opcode      Format
    DE /0       FIADD m16
    DA /0       FIADD m32


    Timing
    Operand       8087         287        387      486     Pentium
    m16        (102-137)+EA  102-137     71-85    20-35    7/4     NP
    m32        (108-143)+EA  108-143     57-72    19-32    7/4     NP