The operating system manages interrupts and exceptions on behalf of the game system in a relatively unobtrusive way. Some interrupts must be handled by the system code itself. Others require further decoding to determine which event has actually occurred when the CPU is interrupted.
The exception handler built into the operating system performs the decoding of interrupts and other exceptions and maps them to system events. If the system event is one that may be handled by the game itself, then a message is sent to an associated event mailbox and the game application is notified. In this way, the game designer can provide an interrupt handler to deal with the exception as required by the game requirements.