My problem is that I have written a code that is supposed to output a result into a set of LEDs connected to the parallel port. When I ran the code it pretty much did nothing. My instructor told me that the code ran too fast that my eyes did not see what happened.
I have found that there are a couple of ways to do a time delay, I have tried to loop the NOP but I think I cannot really determine what is going on. Is there any better way?
I have here a part of the code where I have to add a time delay into:
org 100h
mov ax, 0
mov dx, 378
out dx, ax
mov ax, 1
; 1st
mov cx, 1ah
start1st:
mov ax, 1
left:
out dx, ax
; --------------------------------> how to loop?
mov bx, 2
mul bx
cmp ax, 80h
jl left
dec cx
cmp cx,0
jg start1st
; end 1st
What i finally ended up using was the nop loop
; start delay
mov bp, 43690
mov si, 43690
delay2:
dec bp
nop
jnz delay2
dec si
cmp si,0
jnz delay2
; end delay
I used two registers which I set them both to any high value and its gonna keep on looping until both values go to zero
What I used here was AAAA for both SI and BP, i ended up with roughly 1 second for each delay loop.
Thanks for the help guys, and yes, we still use MS DOS for this assembly language course :(