微机原理-虚拟仿真实验-小键盘输入电路汇编代码

Data  segment PortA equ 408H ; 8255的PA口地址 table db 30h,31h,32h,33h,34h,35h,36h,37h,38h,39h,41h,42h,43h,44h,45h,46h s     db "Watch and test the keyboard on experiment platform. Press any key to end...",0dh,0ah,"$"    ;程序功能提示 Data  ends Code  segment       assume cs:code,ds:data Start:mov ax,data        mov ds,ax       mov dx,offset s    ;显示提示       mov ah,9        int 21h       mov dx, PortA+3       mov al,82H    ;  PA输出 PB输入       out dx,al         ;    l0:mov si,0       mov al,0feh       ;       mov bx,04h    l1:mov dx,PortA       out dx,al       push ax       mov dx,portA+1       in al,dx       mov cx,04h       mov di,0         l2:shr al,1       jc l3       call disp    l3:inc di       loop l2       pop ax       rol al,1       inc si       dec bx       jnz l1       mov ah,0bh       int 21h    ; 检测有无按键，返回AL=0FFh(有按键)或0(无按键)       cmp al,0FFh       jnz l0       mov ah,4ch       int 21h disp proc near      push bx      push si      push di      push ax      push dx      lea bx,table      add si,si      add si,si      add di,si      mov ax,di      xlat        mov dl,al      mov ah,02h      int 21h      pop dx      pop ax      pop di      pop si      pop bx      ret disp endp Code ends      end Start