Hi Ben,

your delay program seems o.k.
So I suppose, the rest of the program cause the error (e.g. interrupts).

Please try a simple test:

org 0
test:
call LONG_DELAY
inc p1
jmp test

LONG_DELAY:
mov r5, #00h
TIME:
mov r4, #00h
WASTE:
djnz r4, WASTE
djnz r5, TIME
ret

insert no other routines and check what happens on P1 (e.g. with LEDs).
At 12MHz P1.7 should change every 16 seconds (P1.6 every 8s, ...).

Also activate no watchdog !


Peter