CSC103 Assembly Language Exercises and Solutions

LOD-C 1

Exercise 1

initialize the contents of several variables to 0

; Exercise 1
; D. Thiebaut
; Initialize the contents of several variables 
; to 55

start:
		lod-c	55		; put 0 in acc
		sto		var1	; store acc in var1
		sto		var2	; store acc in var2
		sto		var3	; store acc in var3
		hlt

@10					; the data section starts here
var1:	        data
var2:	        data
var3:	        data

LOD 10/STO 10

Exercise 2

increment a counter

; Exercise 2
; D. Thiebaut
; A program that sets a counter to 0
; and then increments it
;
start:	lod-c	0		        ; first initialize the counter to 0
		sto	counter

; increment counter
		lod	counter	; get counter in acc
		add-c	1		; add 1 to acc
		sto	counter	; store acc in counter

		hlt

@10						
counter:	data

Exercise 3

compute sum of 3 variables

; Exercise 3
; D. Thiebaut
; Compute the sum of 3 variables
; and stores it into a 4th variable called
; sum.

start:	lod		var1	; get var1 in acc
	add		var2	; add var2 to acc
	add		var3	; add var3 to acc
	sto		sum	; store acc into sum
	hlt

@10
var1:	12
var2:	5
var3:	3
sum:	0

LOD-I 10/STO-I 10

'Exercise 4:

create an index and use it to sum up the same 3 variables

; Exercise 4
; D. Thiebaut
; Compute the sum of 3 variables using an index
; and stores it into a 4th variable called
; sum.  

start:	lod-i 	index	        ; get var1 indirectly in acc
	sto	sum		; set sum to var1
	lod	index	        ; get index in acc
	add-c	1		; increment acc
	sto	index

	lod-i	index	        ; get var2 indirectly in acc
	add	sum	        ; add sum to acc
				; acc now contains var1 + var2
	sto	sum		; store acc in sum

	lod	index	        ; increment index
	add-c	1
	sto	index		

	lod-i	index	        ; get var3 indirectly in acc
	add	sum		; add var3 to sum (which contains var1+var2)
	sto	sum		; store acc back in sum
				; sum now contains var1+var2+var3

	hlt

@15
index: var1		       ; index points to var1
var1:	 12
var2:	 5
var3:	 3
sum:	 0

JMP instruction and labels

Exercise 5

create an infinite loop (incrementing a variable, for example)

; Exercise 5
; D. Thiebaut
; an infinite loop
start:	lod		index	; increment index
		add-c	1
		sto		index		

		jmp		start
		hlt

@15
index:	data		

Exercise 6

create an infinite loop that clears the memory starting at 10

; Exercise 6
; D. Thiebaut
; an infinite loop
start:	lod-c	10		; store 10 in index
	sto	index

loop:	lod-c	55		; acc set to 0
	sto-i	index	        ; store 0 where index is pointing

	lod	index	        ; increment index
	add-c	1
	sto	index		

	jmp	loop	        ; loop forever
	hlt

@9
index:	data

Exercise 7

why does the program of Exercise 6 stop?

JMZ

Exercise 8

write a loop that loops 10 times (use a counter)

Exercise 9

write a loop that stores 55 in the memory locations between 15 and 30