Mohammed, if i am to understand you correctly, you want PULSES to be a 16 bit counter rather than a 8 bit counter. Firstly, if this is the case, doing the multiply is unecessary as you would simply use the value 500 instead of 250.

The code that you posted is a mish-mash of some sample code I expect. It does not make sense to me! I would suggest you do some reading on assembler programming, as I feel you have not grasped some fundamental concepts.


Anyway, if you want to do a 16 bit loop counter, here is one method...

mov PULSES,#.LOW(500)
mov PULSES+1,#.HIGH(500) ;load count
loop:
djnz PULSES,lp1 ;low--
dec PULSES+1 ;if low==0,high--
lp1:
mov a,PULSES ;get low
orl a,PULSES+1 ; low | high
jnz loop ;if counter is not equal to 0

PULSES .DS 2 ;PULSES now occupies 2 bytes