实验4 8086标志寄存器及中断
实验任务1
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 start
答:不能替换,因为add会改变CF的值,使进位出错。
实验截图:
实验任务2
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
实验截图:
问题:
(1)输入字符到al,存入[si],和#比较,相等进入next,不相等继续循环。
(2)输出换行符。
(3)输出字符si次,由于最后一次si没有增加,最后的#不输出。
实验任务3
源代码:
assume ds:data, cs:code, ss:stack
data segment
x dw 91, 792, 8536, 65535, 2021, 0
len equ $ - x
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 di, offset x
mov cx, len/2 ; len/2处理数量
foreach:
mov ax, word ptr ds:[di]
push cx
call printNumber
pop cx
mov ah, 2
mov dl, 20h
int 21h
add di, 2
loop foreach
mov ah, 4ch
int 21h
;ax:输入数字
printNumber:
mov bx, 0
num:
mov dx, 0
mov bp, 10
div bp;dxax/bp得ax商 dx余数
push dx;余数 即末位
inc bx;存储数字位数
cmp ax, 0
je next
jmp num
next:
mov cx, bx;数字位数
print:
pop dx
add dl, 30h;转成为字符
mov ah, 2
int 21h
loop print
ret
code ends
end start
实验截图:
实验任务4
源代码:
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
实验截图:
实验任务5
源代码:
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
实验截图:
实验任务6
实验截图:
通过编译连接运行task6_1.asm
和task6_2.asm
后可以看到,屏幕底部出现了绿色的"welcome to 2049!
",说明42号中断程序被成功调用。