FINCSTP         Increment FP stack pointer           Exceptions: None
                                                     C3 C2 C1 C0: ? ? 0 ?
FINCSTP

        Logic   TOP ← (TOP + 1) AND 07h

    FINCSTP adds one to the three-bit TOP field of the FPU status word.
    In effect, FINCSTP rotates the stack; it is not equivalent to
    popping a register from the stack. If TOP is 7, this instruction
    makes it 0.


    Opcode      Format
    D9 F7       FINCSTP


    Timing
    Operand       8087         287        387      486     Pentium
    -             6-12         6-12       21        3       1      NP