Compilation and debugging of assembly source program for multiple logic segments

Experimental task 1

• Task 1-1

  To program task1_1.asm assembles and connects, loads and tracks debugging with debug, and answers questions based on the results.

  assume ds:data, cs:code, ss:stack
  
  data segment
      db 16 dup(0)
  data ends
  
  stack segment
      db 16 dup(0)
  stack ends
  code segment
  start:
      mov ax, data
      mov ds, ax
  
      mov ax, stack
      mov ss, ax
      mov sp, 16
  
      mov ah, 4ch
      int 21h
  code ends
  end start
  

  Question 1:
  View register value
  Use the U command to view the disassembly code, find the memory address of mov ah,4ch, and use the G command to quickly execute before this command.
  
  (DS)=076C
  (SS)=076D
  (CS)=076E
  Question 2:
  Assuming that the CODE segment address is X after the program is loaded, the data segment address is X-2 and the stack segment address is X-1
  Since the memory space occupied by the program is continuous, and the segment size accounts for an integer multiple of 16 bytes, according to the code of task1-1.ASM, data is next to the segment prefix, stack is next to data, and code is next to stack.

• Task 1-2
  To program task1_2.asm assembles and connects, loads and tracks debugging with debug, and answers questions based on the results.

  assume ds:data, cs:code, ss:stack
  data segment
      db 4 dup(0)
  data ends
  
  stack segment
      db 8 dup(0)
  stack ends
  code segment
  start:
      mov ax, data
      mov ds, ax
  
      mov ax, stack
      mov ss, ax
      mov sp, 8
  
      mov ah, 4ch
      int 21h
  code ends
  end start
  

  Question 1:
  Repeat the operation of question 1 in task1-1 to view the register value
  
  (DS)=076C
  (SS)=076D
  (CS)=076E
  Question 2:
  Assuming that the CODE segment address is X after the program is loaded, the data segment address is X-2 and the stack segment address is X-1
  Since the memory space occupied by the program is continuous, and the segment size accounts for an integer multiple of 16 bytes, according to the code of task1-2.ASM, data is next to the program segment prefix, stack is next to data, and code is next to stack.

• Task 1-3
  To program task1_3.asm assembles and connects, loads and tracks debugging with debug, and answers questions based on the results.

  assume ds:data, cs:code, ss:stack
  data segment
  db 20 dup(0)
  data ends
  stack segment
  db 20 dup(0)
  stack ends
  code segment
  start:
  mov ax, data
  mov ds, ax
  
  mov ax, stack
  mov ss, ax
  mov sp, 20
  
  mov ah, 4ch
  int 21h
  code ends
  end start
  

  Question 1:
  Repeat the operations of task1-1 and task1-2, and the results are as follows
  
  (DS)=076C
  (SS)=076E
  (CS)=0770
  Question 2:
  Assuming that the CODE segment address is X after the program is loaded, the data segment address is x-4 and the stack segment address is X-2
  Since the memory space occupied by the program is continuous, and the segment size accounts for an integer multiple of 16 bytes, according to the code of task1-3.ASM, data is next to the program segment prefix, stack is next to data, and code is next to stack.

• Tasks 1-4
  To program task1_4.asm assembles and connects, loads and tracks debugging with debug, and answers questions based on the results.

  assume ds:data, cs:code, ss:stack
  code segment
  start:
  mov ax, data
  mov ds, ax
  
  mov ax, stack
  mov ss, ax
  mov sp, 20
  
  mov ah, 4ch
  int 21h
  code ends
  
  data segment
  db 20 dup(0)
  data ends
  
  stack segment
  db 20 dup(0)
  stack ends
  end start
  

  Question 1:
  Repeat the operation to view the register value
  
  (DS)=076E
  (SS)=0770
  (CS)=076C
  Question 2:
  Assuming that the CODE segment address is X after the program is loaded, the data segment address is x + 2 and the stack segment address is X+4
  Since the memory space occupied by the program is continuous, and the segment size accounts for an integer multiple of 16 bytes, if the code according to task1-4.ASM is next to the program segment prefix, data is next to code, and stack is next to data.

• Tasks 1-5
  Based on the practice and observation of the above four experimental tasks, summarize and answer:
  ① For the segment defined below, after the program is loaded, the actual memory space allocated to the segment is \ (Ceil(N/16) \).

  xxx segment
  db N dup(0)
  xxx ends