Simple If.. Then help:

[Bruce]

What do you get with something like this?

TRISA = %00000011
TRISB = %00000000
loop1:
   if PORTA.0 = 1 then
      PORTB.0 = 1
   else
      PORTB.0 = 0
   endif
   high PORTB.1
   goto loop1
   end

Your code as-is will never clear PORTB.0 to indicate PORTA.0 is at ground.

You could even simplify this with PORTB.0 = PORTA.0 to reflect the logic
input on RA0 to RB0.. or the inverse with PORTB.0 = ~PORTA.0.