Have you ever received a phone call and when the call was over forgot what you were doing when the call came in? We do not want the PIC to have that problem.
I've had conversations lately where I've gone off track for a moment and completely forgot the main thread of what I was saying, I think the Interrupt handler in my brain need dubugin

The PBP manual has a section in the back about interrupts in ASM, Read it along with the code.
Page 200 in the manual, I'm reading it and trying to work through the code. Bruce's code is exactly the same well very similar, with the Interrupt block in the middle added.

Thanks for the pointer mackrackit.

Dave