Question

Write an Intel 8085 assembly program to find the largest of N numbers stored in memory using the algorithm below. Hand trace (execute) the program showing the changes made to all affected registers and memory locations.

Max = a(1)

For i = n to N

If max < a(i) then max = a(i)

Next i

Answer 1

                ALGORITHM:

1) Load the address of the first element of the array in HL pair

2) Move the count to B – reg.

3) Increment the pointer

4) Get the first data in A – reg.

5) Decrement the count.

6) Increment the pointer

7) Compare the content of memory addressed by HL pair with that of A - reg.

8) If Carry = 0, go to step 10 or if Carry = 1 go to step 9

9) Move the content of memory addressed by HL to A – reg.

10) Decrement the count

11) Check for Zero of the count. If ZF = 0, go to step 6, or if ZF = 1 go to next step.

12) Store the largest data in memory.

13) Terminate the program.

PROGRAM

PROGRAM	Description
LXI H,4200	Set pointer for array
MOV B,M	Load the Count
INX H	Set 1st element as largest data
MOV A,M	Copy data from register M to accumulator
DCR B	Decrements the count
LOOP:     INX H	Increment of HL pair by 1
CMP M	f A- reg > M go to AHEAD
JNC AHEAD	Jump to AHEAD if carry is not = 1
MOVA,M	the new Set value as largest
AHEAD: DCR B	Decrement B
JNZ LOOP	Repeat comparisons till count = 0
STA 4300	Repeat comparisons till count = 0
HLT	Stop program