N       	equ     	20      	; array count

        	org     	$1000    	; starting address of on-chip SRAM
sum		rmb	2		; array sum
i       	rmb     	1       	; array index

        	org     	$1500   	; starting address of the program
        	ldaa    	#0
        	staa   	 i       	; initialize loop (array) index to 0
        	staa    	sum     	; initialize sum to 0
        	staa    	sum+1  		;       "

loop		ldab	i
        	cmpb    	#N      	; is i = N?
        	beq     	done    	; if done, then branch
       	ldx     	#array  	; use index register X as a pointer to the array
        	abx            		; compute the address of array[i]
        	ldab    	0,x     	; place array[i] in B
        	ldy     	sum     	; place sum in Y
        	aby            		; compute sum <- sum + array[i]
       	sty     	sum     	; update sum
        	inc    	i       	; increment the loop count by 1
        	bra    	 loop
done		swi		; return to D-Bug12 monitor

array		db	1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20
        	end