INT 04h (4)              Overflow

Called when either an INTO (Interrupt on Overflow) instruction is
encountered and the Overflow Flag (OF) is set, or when an INT 4
instruction is encountered.

This service gives programmers a way to provide a common handler for
all arithmetic overflow conditions. By executing an INTO instruction
after any arithmetic operation, a program can ensure that overflow
conditions are properly handled.

INT 04h (4) Overflow