定制键盘输入处理

在屏幕上显示a-z，按下esc时变色

assume cs:code,ds:data,ss:stk
data segment
	dw 0,0
data ends

stk segment
	db 123 dup (0)
stk ends

code segment
start:
	mov ax,data
	mov ds,ax
	
	mov ax,stk
	mov ss,ax
	mov sp,128
	
	mov ax,0
	mov es,ax       ;改变中断例程地址
	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   ;显示a-z
	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,4c00h
	int 21h
	
delay:push ax   ;延时程序
      push dx
	  mov dx,10h
	  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

int9:push ax
	 push bx
	 push es

	 in al,60h;自定义int9中断,模拟中断调用例程

	 pushf    ;标志寄存器入栈 
	 
	 pushf	  ;设置IF,TF值为0
	 pop bx
	 and bh,11111100b
	 push bx
	 popf
	 
	 call dword ptr ds:[0]
	 
	 cmp al,1 ;esc扫描码为1
	 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