Experiment 2 compilation and debugging of assembly source program of multiple logic segments

Experimental task 1

  Task 1-1

  task1_1.asm source code
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

task1_1 screenshot before the end of line17 and line19

 

 

①   In debug, execute until the end of line17 and before line19. Record this time: register (DS) =_ 076A_, Register (SS)=__ 076B__, Register (CS)=_ 076C_.

 

②   Assuming that the segment address of the code segment is X after the program is loaded, the segment address of the data segment is X__ X-2__, The segment address of stack is__ X-1__ .

Task 1-2

Task task1_2.asm source code

assume ds:data, cs:code, ss:stack 

data segment 
    db 4 dup(0)     ; Four byte units are reserved, and the initial value is 0 
data ends 

stack segment 
    db 8 dup(0)     ; 8 byte units are reserved, and the initial values are 0 
stack ends 
code segment 
start:
    mov ax, data 
    mov ds, ax 

    mov ax, stack 
    mov ss, ax 
    mov sp, 8        ; Set stack top 

    mov ah, 4ch 
    int 21h 
code ends 
end start

task1_2. After debugging to the end of line17 and before line19, observe the screenshot of register DS, CS and SS values

 

 

①   In debug, execute until the end of line17 and before line19. Record this time: register (DS) =__ 076A__, Register (SS)=_ 076B__, Register (CS) =__ 076C__

 

②   Assuming that the segment address of the code segment is X after the program is loaded, the segment address of the data segment is X__ X-2__, The segment address of stack is__ X-1__

Task 1-3

Task task1_3.asm source code

assume ds:data, cs:code, ss:stack
data segment
db 20 dup(0) ; 20 byte units are reserved, and the initial values are 0
data ends
stack segment
db 20 dup(0) ; 20 byte units are reserved, and the initial values are 0
stack ends
code segment
start:
mov ax, data
mov ds, ax
mov ax, stack
mov ss, ax
mov sp, 20 ; Set initial stack top
mov ah, 4ch
int 21h
code ends
end start

task1_3. Screenshot of the values of registers DS, CS and SS before the end of debugging to line17 and line19

 

 

①   In debug, execute until the end of line17 and before line19. Record this time: register (DS) =__ 076A_, Register (SS)=__ 076C__, Register (CS) =__ 076E__

②   Assuming that the segment address of the code segment is X after the program is loaded, the segment address of the data segment is X__ X-4__, The segment address of stack is__ X-2__.

Tasks 1-4

 

Source code:

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

 

 

①   In debug, execute until the end of line9 and before line11. Record this time: register (DS) =__ 076C__, Register (SS)=__ 076E__, Register (CS) =_ 076A_

②   Assuming that the segment address of the code segment is X after the program is loaded, the segment address of the data segment is X__ X+2__, The segment address of stack is_ X+4__.

Tasks 1-5

①     For the segment defined below, after the program is loaded, the actual memory space allocated to the segment is   16*ceil(N/16) .

②     task1_4.asm can still be executed correctly, because the entry of the original program is described after end. If it is empty, the program will be executed from scratch, only Task1_ The beginning of 4 is the content of the code segment.

Experimental task 2

Source code:

assume cs:code
code segment
    mov ax,0b800h
    mov ds,ax
    mov bx,0f00h
    mov cx,160
s:  mov ax,0304h
    mov [bx],al
    inc bx
    loop s

mov ax,4c00h
int 21h
code ends
end

Screenshot of operation results

Experimental task 3

Complete assembly source code
assume cs:code
data1 segment
    db 504850500484904849 ; ten numbers
data1 ends

data2 segment
    db 000047004700       ; ten numbers
data2 ends

data3 segment
    db 16 dup(0)
data3 ends

code segment
start:
    mov ax,data3
    mov ds,ax
    mov ax,data1
    mov es,ax

    mov cx,10
    mov bx,0
s1: mov al,es:[bx]
    add [bx],al
    inc bx
    loop s1

    mov ax,data2
    mov es,ax

    mov cx,10
    mov bx,0
s2: mov al,es:[bx]
    add [bx],al
    inc bx
    loop s2

    mov ah,41h
    int 21h

code ends
end start

Screenshot of loading, disassembling and debugging in debug:

  After the data items are added in turn, the debug command and screenshot of the original value of memory space data corresponding to logical segments data1, data2 and data3:

Experiment task 4:

Complete source code

assume cs:code

data1 segment
    dw 2, 0, 4, 9, 2, 0, 1, 9
data1 ends 

data2 segment
    dw 8 dup(?)
data2 ends

code segment
start:
    
    mov ax,data1
    mov ds,ax

    mov ax,data2
    mov ss,ax
    mov sp,16

    mov cx,8
    mov bx,0

    s:
      push [bx]
      add bx,2
    loop s

    mov ah, 4ch
    int 21h
code ends
end start

 

  Before and after execution

Experimental task 5

Source code:

assume cs:code, ds:data
data segment
        db 'Nuist'
        db 5 dup(5)
data ends

code segment
start:
        mov ax, data
        mov ds, ax

        mov ax, 0b800H
        mov es, ax

        mov cx, 5
        mov si, 0
        mov di, 0f00h
s:      mov al, [si]
        and al, 0dfh
        mov es:[di], al
        mov al, [5+si]
        mov es:[di+1], al
        inc si
        add di, 2
        loop s

        mov ah, 4ch
        int 21h
code ends
end start

Screenshot of operation results:

 

   Use the debug tool to debug the program, and use the g command to execute it once before the program returns (i.e. after ine25 and before line27):

 

 

What is the function of line19 in the source code?

  A: if the lower address is a lowercase letter, turn it into an uppercase letter. By bitwise and, turn the fifth bit of the binary Ascii code corresponding to the lowercase letter into 0, that is, subtract 32 from the Ascii value to become an uppercase letter.

What is the purpose of the byte data in the data segment line4 in the source code?

  A: set the color of the word.

Experimental task 6

task6.asm source code
assume cs:code, ds:data

data segment
    db 'Pink Floyd      '
    db 'JOAN Baez       '
    db 'NEIL Young      '
    db 'Joan Lennon     '
data ends

code segment
start:
    mov ax,data
    mov ds,ax

    mov cx,4
    mov bx,0
s:  mov dx,[bx]
    mov ax,dx
    add al,32
    mov [bx],ax
    add bx,16
    loop s

   mov ah, 4ch
   int 21h
code ends
end start

Load, disassemble and debug screenshots in debug

 

 

 

Experimental task 7

task7.asm source code
assume cs:code, ds:data, es:table

data segment
    db '1975''1976''1977''1978''1979' ;20 bytes per line
    dw  162238213562390
    dw  3791328 
data ends

table segment
    db 5 dup( 16 dup(' ') )  ;
table ends

code segment
start:
    mov ax,data
    mov ds,ax
    mov ax,table
    mov es,ax

    mov bx,0
    mov si,0
    mov bp,0
    mov di,0
    

    mov cx,5
s:  mov ax,[bx+si]              ;1975
    mov es:[bp+di],ax    
    add si,2
    add di,2
    mov ax,[bx+si]    
    mov es:[bp+di],ax 

    mov ax,0                    ;[sp]0016[sp]
    add ax,cx
    add ax,cx
    add ax,8
    add si,ax                   ;Here to implement y=8+2n To track this specific si How much,among n by cx Value of
    add di,2
    mov ax,[bx+si]              ;ax Store 16 bit divisor
    mov dl,32
    mov dh,00h
    mov es:[bp+di],dx
    add di,2
    mov dl,00h
    mov dh,al
    mov es:[bp+di],dx
    add di,2
    mov dl,ah
    mov dh,32
    mov es:[bp+di],dx

    add si,10
    add di,2
    mov dx,[bx+si]              ;dl Stored divisor
    mov es:[bp+di],dx

    add di,2
    div dl                      ;al Depositors, ah Deposit remainder
    mov dl,32
    mov dh,al
    mov es:[bp+di],dx
    add di,2
    mov dl,00h
    mov dh,32
    mov es:[bp+di],dx

    add bx,4                    ;Next cycle initialization
    add bp,16
    mov si,0
    mov di,0

    loop s

    mov ah, 4ch
    int 21h
code ends
end start
Debug screenshot
(1) View screenshot of original data information of table segment
(2) Run in debug until the program exits, use the d command to view the screenshot of the memory space corresponding to the table segment, and confirm whether the information is structurally written to the specified memory as required

 

 

 

 

 

 

 

Posted by ibo on Thu, 11 Nov 2021 11:34:21 -0800