实验4 8086标志寄存器及中断

实验一

代码：

assume cs:code, ds:data

data segment
   x dw 1020h, 2240h, 9522h, 5060h, 3359h, 6652h, 2530h, 7031h
   y dw 3210h, 5510h, 6066h, 5121h, 8801h, 6210h, 7119h, 3912h
data ends
code segment
start:
    mov ax, data
    mov ds, ax
    mov si, offset x
    mov di, offset y
    call add128

    mov ah, 4ch
    int 21h

add128:
    push ax
    push cx
    push si
    push di

    sub ax, ax

    mov cx, 8
s:  mov ax, [si]
    adc ax, [di]
    mov [si], ax

    inc si
    inc si
    inc di
    inc di
    loop s

    pop di
    pop si
    pop cx
    pop ax
    ret
code ends
end star

① line31~line34的4条inc指令，能否替换成如下代码？你的结论的依据是什么？

不能，add会影响进位标志符CF，而inc则不会改变CF的值

 

实验二

代码：

assume cs:code, ds:data
data segment
        str db 80 dup(?)
data ends

code segment
start:  
        mov ax, data
        mov ds, ax
        mov si, 0
s1:        
        mov ah, 1
        int 21h
        mov [si], al
        cmp al, '#'
        je next
        inc si
        jmp s1
next:
        mov ah, 2
        mov dl, 0ah
        int 21h
        
        mov cx, si
        mov si, 0
s2:     mov ah, 2
        mov dl, [si]
        int 21h
        inc si
        loop s2

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

 

① 汇编指令代码line11-18，实现的功能是？　

接收输入字符并保存到ds段中，直到输入字符为‘#’且不包含‘#’

② 汇编指令代码line20-22，实现的功能是？

打印换行符号

③ 汇编指令代码line24-30，实现的功能是？

打印出ds中的字符

实验三

代码：

 

assume cs:code,ds:data,ss:stack
data segment
    x dw 91, 792, 8536, 65521, 2021
    len equ $ - x
data ends
stack segment
    dw 8 dup(0)
stack ends
code segment
start:
    mov ax, data
    mov ds, ax
    mov si, offset x
    mov ax, stack
    mov ss, ax
    mov sp, 16

    mov cx, len/2
    mov bx, 10
s:    mov ax, word ptr ds:[si]
    push cx
    call printNumber
    call printSpace
    add si,2
    pop cx
    loop s

    mov ax, 4c00h
    int 21h

printNumber:
    mov cx, 0
s1:    mov dx, 0
    div bx
    push dx
    inc cx　　　　　　
    or ax,0　　　　
    jnz s1　　　

s2:    pop dx
    add dl, 30h
    mov ah, 2
    int 21h
    loop s2

    ret

printSpace:
    mov ah, 2
    mov dl, ' '
    int 21h
    ret

code ends
end start

 

 实验四

代码：

assume cs:code,ds:data
 
data segment
 
    str db "assembly language, it's not difficult but tedious"
 
len equ $ - str
 
data ends
 
stack segment   
 
    db 8 dup(?)
 
stack ends
 
code segment
 
start:    
 
    mov ax, data   
 
    mov ds, ax   
 
    mov si, 0   
 
    mov cx, len      
 
    call strupr       
 
    call printStr 
 
    mov ax, 4c00h   
 
    int 21h
strupr :       
 
    push cx   
 
    push si       
 
transform:       
 
    mov al, ds:[si]
 
    cmp al, 97 
 
    jl continue  
 
    cmp al, 122 
 
    jg continue   
 
    and al, 0dfh   
 
    mov ds:[si], al
 
continue:       
 
    inc si        
 
    loop transform
 
    pop si   
 
    pop cx      
 
    ret       
 
printStr:   
 
    push cx  
 
    push si    
print:   
 
    mov ah, 2       
 
    mov dl, ds:[si]       
 
    int 21h       
 
    inc si   
 
    loop print    
 
    pop si         
     
    pop cx   
 
    ret          
 
code ends
 
end start   

 

 实验五

代码：

assume cs:code, ds:data

data segment
    str1 db "yes", '$'
    str2 db "no", '$'
data ends

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

    mov ah, 1
    int 21h　　　　

    mov ah, 2
    mov bh, 0
    mov dh, 24
    mov dl, 70
    int 10h　　　　

    cmp al, '7'
    je s1　　　　　　
    mov ah, 9
    mov dx, offset str2　　　　
    int 21h

    jmp over

s1: mov ah, 9
    mov dx, offset str1　　　
    int 21h
over:  
    mov ah, 4ch
    int 21h
code ends
end start

 

 

实验六

代码：

assume cs:code

code segment
start:
    ; 42 interrupt routine install code
    mov ax, cs
    mov ds, ax
    mov si, offset int42  ; set ds:si

    mov ax, 0
    mov es, ax
    mov di, 200h        ; set es:di

    mov cx, offset int42_end - offset int42
    cld
    rep movsb

    ; set IVT(Interrupt Vector Table)
    mov ax, 0
    mov es, ax
    mov word ptr es:[42*4], 200h
    mov word ptr es:[42*4+2], 0

    mov ah, 4ch
    int 21h

int42: 
    jmp short int42_start
    str db "welcome to 2049!"
    len equ $ - str

    ; display string "welcome to 2049!"
int42_start:
    mov ax, cs
    mov ds, ax
    mov si, 202h

    mov ax, 0b800h
    mov es, ax
    mov di, 24*160 + 32*2

    mov cx, len
s:  mov al, [si]
    mov es:[di], al
    mov byte ptr es:[di+1], 2
    inc si
    add di, 2
    loop s

    iret
int42_end:
   nop
code ends
end start

assume cs:code

code segment
start:
    int 42

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

 

代码：

assume cs:code

code segment
start:
    int 42

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