FFREE           Free register                        Exceptions: None
                                                     C3 C2 C1 C0: ? ? ? ?
FFREE destination

        Logic   TAG(i) ← 11 binary

    FFREE tags the destination register as empty. It does not affect the
    contents of the destination register, nor does it affect the FP
    stack-top pointer (TOP).


    Opcode      Format
    DD C0 + i   FFREE ST(i)


    Timing
    Operand       8087         287        387      486     Pentium
    reg           9-16         9-16       18        3       1      NP