ex9a1
From the output, we can see that the keyboard press will trigger the interupt and the counter will increase every keyboard press.

ex9a2
The dummy task has a higher priority than the task which handle the interupt. But when the interupt is trigged, it will run the interupt first as the urgency and it become priority 257.

ex9b
Firstly, we need to enable the interupt from the parallel port. Every key press in the parallel port, it will increase the counter.