RWM again lol.

Some ideas...

Slower, but at least it’s 50% duty cycle
Code:
‘ Not RWM safe!

flipflop var bit

cycle:
flipflop = flipflop + 1
portb.0 = flipflop
goto cycle
can you afford to waste a whole port?
Code:
‘ Is RWM safe!

flipflop var byte
flipflop = %01010101

cycle:
portb = flipflop
@comf _flipflop
goto cycle
faster than what you posted above.
You need two consecutive nop instructions to balance the goto for %50 duty cycle in the loop you posted.