Question

Question 2.1) Consider the following program: [3 marks] ORG $7000 dc.b $11,$22,$33,$44,$55,$66,$77 LDS #$ 1000 LDX #$ 7000 LDAB #$7 LOOP1: LDAA 0,X PSHA INX DECB BNE LOOP1 LDX #$ 7000 LDAB #$7 LOOP2: PULA STAA 0,X INX DECB BNE LOOP2 WAI

Can anybody briefly explain what this assembly program does?

Answer 1

The program given is used here to reverse the values in the memory location.

The values start from memory location $7000.

There are 7 elements.

Now all this 7 elements are pushed into a stack.

I.e last value of 7 elements(value at $7006) is at top of the stack.

This operation is done in loop1.

After that, the values in stack are pulled one by one and stored into memory location starting from $7000. (In loop 2)

As stack follows last in first out, the values stored in memory location after complete program will be in reverse order of initial values in location.

This program is operated to reverse the values in memory location $7000-$7006