Interrupt fires when module is unloaded

I am trying to figure out interrupts by writing a shadow of Rubini's 'short' program. Recall that Rubini tells us to enable parallel port interrupts by wiring pins 9&10 together, then writing binary data to the parallel port's address. I am doing that, but: - I don't see interrupts when I write to the port - I do see one interrupt when I unload the driver (in the fop's .release method) - This happens whether or not the pins are wired up. What is going on here?