INT 04H: Overflow Interrupt

 The INT 04H vector can be used as one way to minimize the size of programs
 that perform a lot of arithmetic operations.

 After any arithmetic operation, the INTO instruction will test for
 arithmetic overflow, and if the CPU flag is set (OF=OV=1), then INT 04H
 is executed.

 You might see code such as:

          mov     ax,var_1
          add     ax,var_2
          into              ;2-byte test for arithmetic overflow
      ... etc. ...          ;either no overflow or it has been handled
                            ; by the interrupt handler

See Also: INT 00H (division by 0)
          ROM-BIOS Functions
          DOS Functions