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INTO             Interrupt on Overflow               Flags: O D I T S Z A P C
                                                            0 0
INTO

          Logic:    if (OF = 1)
                        PUSHF              ; Push flags onto stack
                        TF . 0             ; Clear Trap Flag
                        IF . 0             ; Disable Interrupts
                        CALL FAR (10h)     ; The INTO vector is at 0000:0010h

    INTO activates interrupt type 4 if the Overflow Flag is set; otherwise
    it does nothing. This interrupt operates identically to an "INT 4" if
    the overflow flag is set, in which case INTO pushes the flags
    register, clears the Trap and Interrupt-enable Flags, pushes CS and
    IP, then transfers control to the interrupt-num 4 handler, which is
    pointed to by the vector at location 10h.  If the interrupt handler
    returns using an IRET instruction, the original flags are restored.

  --------------------------------------------------------------------------
   Operands                  Clocks   Transfers  Bytes   Example
                           byte(word)
   no operands              53 or 4       5        1     INTO
  --------------------------------------------------------------------------

       Notes:         The flags are stored in the same format as that used
                      by the PUSHF instruction.

                      INTO can be used after an operation that may cause
                      overflow, to call a recovery procedure.