;*******************************;
;* 中断实验 *;
;*******************************;

data segment
mess db 'TPCA interrupt!',0dh,0ah,'$'
data ends
code segment
assume cs:code,ds:data
start:
mov ax,cs
mov ds,ax
mov dx,offset int3
mov ax,250bh
int 21h

in al,21h
and al,0f7h
out 21h,al
mov cx,10
sti
ll: jmp ll
int3:
mov ax,data
mov ds,ax
mov dx,offset mess
mov ah,09
int 21h
mov al,20h
out 20h,al
loop next
in al,21h
or al,08h
out 21h,al
sti
mov ah,4ch
int 21h
next: iret
code ends
end start
这个程序我不太明白，究竟是怎么样运行的？那个ll: jmp ll岂不是一个死循环？