1) Consider the following program segment given below:

Question

1) Consider the following program segment given below:
			ORG 0x0400
    Address
    0400h                 MOV SP, 0460H
                                MOV AL, 1
                                MOV BX, 0
                                MOV CX, 7
     AGAIN:              CALL SHERIDAN
     0420H                SHL AL, 1
                                OUT 0, AL
                                LOOP AGAIN
                                INT3
SHERIDAN:
                  PUSH CX
                  MOV CX, AABBH
                  LOOP $
                  POP CX 
                  RET
In executing the above program, the Microprocessor is using the stack. In that respect, draw the stack along with its content for the duration of the program execution.

Draw the stacks and explain each stack

GPT 3.5 · Answer

To draw the stack and explain each stack, we need to analyze the program segment step by step and track the changes in the stack.

1) Initially, the stack pointer (SP) is moved to 0460h. This means the stack starts from address 0460h and grows downwards.

| |
| ... |
| | <- SP (0460h)
+---------+

2) The program then moves the value 1 into the AL register.

3) The program moves the value 0 into the BX register.

4) The program moves the value 7 into the CX register.

5) The program calls the subroutine SHERIDAN.

| ... |
| ... |
| ... |
| ADDR |
+---------+
| ... |
| BBBBh | <- CX
| ... |
+---------+

6) The program shifts the AL register left by 1 bit.

7) The program outputs the value of AL (1) to the port 0.

8) The program loops back to the label AGAIN if CX is not zero. This creates a loop, repeating steps 6-8 seven times.

| ... |
| ... |
| ... |
| ADDR |
+---------+
| ... |
| XXXX | <- CX, where XXXX is the value of CX at the end of the loop
| ... |
+---------+

9) When the loop ends, the program encounters the INT3 instruction, which triggers a software interrupt.

10) The program jumps to the beginning of the SHERIDAN subroutine.

| ... |
| ... |
| ... |
| ADDR |
+---------+
| SHERIDAN | <- ADDR
| BBBBh | <- CX
| ... |
+---------+

11) The SHERIDAN subroutine pushes the value of CX onto the stack.

| ... |
| ... |
| ... |
| SHERIDAN |
+---------+
| ... |
| BBBBh | <- CX
| ... |
+---------+

12) The SHERIDAN subroutine moves the value AABBh into CX.

| ... |
| ... |
| ... |
| SHERIDAN |
+---------+
| ... |
| AABBh | <- CX
| ... |
+---------+

13) The SHERIDAN subroutine loops back to itself.

14) The SHERIDAN subroutine pops the value of CX from the stack.

| ... |
| ... |
| ... |
| ADDR |
+---------+

15) The SHERIDAN subroutine returns.

At this point, the program execution ends, and the stack will look like:

| ... |
| ... |
| ... |
| |
+---------+