 assume cs:code
stack segment
db 128 dup (0)
stack ends
data segment
dw 0,0
data ends
code segment
start:
mov ax,stack
mov ss,ax
mov sp,128
mov ax,data
mov ds,ax
mov ax,0
mov es,ax
push es:[9*4]
pop ds:[0]
push es:[9*4+2]
pop ds:[2]
mov WORD ptr es:[9*4],offset int9
mov es:[9*4+2],cs
mov ax,0b800h
mov es,ax
mov ah,'a'
s:
mov es:[160*12+40*2],ah
call delay
inc ah
cmp ah,'z'
jna s
mov ax,0
mov es,ax
push ds:[0]
pop es:[9*4]
push ds:[2]
pop es:[9*4+2]
mov ax,4c00h
int 21h
delay:
push ax
push bx
mov dx,1000h
mov ax,0
s1:
sub ax,1
sbb dx,0
cmp ax,0
jne s1
cmp dx,0
jne s1
pop dx
pop ax
ret
;-------新的int 9中断例程-------
int9:
push ax
push bx
push es
in al,60h
pushf
pushf
pop bx
and bh,11111100b
push bx
popf
call DWORD ptr ds:[0]
cmp al,1 ;这里的al在哪里改变的呀?
jne int9ret
mov ax,0b800h
mov es,ax
inc BYTE ptr es:[160*12+40*2+1]
int9ret:
pop es
pop bx
pop ax
iret
code ends
end start
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