中断调用处理程序

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

stack segment

db 256 dup (?)

top label word

stack ends

data segment

db 'xiaonei',0

data ends

code segment

start:

mov ax,stack

mov ss,ax

mov sp,offset top

;将sqr程序到sqrend程序存入内存0：200处

mov ax,cs

mov ds,ax

mov si,offset converter

mov ax,0

mov es,ax

mov di,200H

mov cx,offset converterend - offset converter

cld

rep movsb

;安装向量表，安装到中断码为7c处

mov ax,0

mov es,ax

mov word ptr es:[7cH*4],200H

mov word ptr es:[7cH*4+2],0

int 7cH ;调用中断处理程序

mov ax,4c00H

int 21H

;将data段中的字符串"xiaonei"转换成大写

converter:

push cx ;将冲突的寄存器保存到栈中

mov ax,data

mov ds,ax

mov bx,0

s0:

mov cl,[bx]

mov ch,0

jcxz s1

and cl,0dfH

mov [bx],cl

inc bx

jmp short s0

s1:

pop cx

iret

converterend:

nop

code ends

end start