4 Wire resistive touch screen, Need help

[Art]

I can't see why you'd use an interrupt for a touch screen,
and if there is a valid reason I'd like to know what it is.

Why not follow the way 2D games work?

1) Draw current frame to screen,

2) Check for user input,

3) act on user input, and apply any movement/calculations for next frame,

4) goto step one.

It would seem if you're using an interrupt, and your program is in the middle of step 3
while receiving new input you are complicating things.