$(20$ points$)$ Write the COMPLETE main program and IRQ$-$ISR $($IRQ Interrupt Service Routine$)$ such

that

a$)$ the main program will first initialize the hardware, and variables and registers $($including the RESULT

variable$),$ then will continuously output the sequence $$00,$$$FF,$$$00,$$FFdots on port $C.$

b$)$ the IRQ$-$ISR will count the number of interrupts $($i$.$e$.,$ the number of times the IRQ$-$ISR is called$)$ and

store the $16-$bit count result in the RESULT variable.

Assume that the external I$/$O hardware uses only the IRQ pin $($assuming a level$-$sensitive IRQ$)$ to

synchronize with the processor. Also, make sure that the IRQ vector is set properly. It might be a good

idea to simulate your program using Wookie $($see the software tutorial on the course web page on how to

simulate the $\frac{\text{I}}{O}$ and interrupts$).$

MAIN

ORG $$C000$