Event writing in Win [ Repost - answered elsewhere ]

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Visual-Studio

I want to write a event at a program in Win xp environment that is triggered when a pulse send to a special port of copmuter.
but events that write at visual programing in class modules should be raised inside a standard event of other component and
don't work independently.
in DOS environment it can write with interrupts and programing interrupts but in win xp i want to know how can I do that?
so I would appreciate it if you advise me about this problem.