实验目的
熟悉星研集成开发环境，掌握微机接口程序编写调试的基本方法。
掌握矩阵式键盘工作原理及识别按键的方法。
掌握8段数码管显示数字或字符的工作原理和它的使用方法。
掌握用8255扫描键盘及用8255刷新数码管的显示方法。
实验要求
在2*8（看着像4*4，实际上是2*8）的小键盘上按下按键，该键的值同时显示在8个数码管上。按键松开时显示上一次的按键值。
.Model tiny .data .stack 100 segtab db 0c0h,0f9h,0a4h,0b0h,99h,92h,82h,0f8h,80h,90h,88h,0h,0c6h,40h,86h,8eh keycode dw 0fe02h,0fd02h,0fb02h,0f702h,0ef02h,0df02h,0bf02h,7f02h dw 0fe01h,0fd01h,0fb01h,0f701h,0ef01h,0df01h,0bf01h,7f01h .CODE start: mov ax,@data mov ds,ax mov es,ax mov dx,273h mov al,81h out dx,al wait1: call scankey cmp ax,-1 jz wait1 call translate call led_disp jmp wait1 mov ax,4c00h int 21h scankey proc near push cx push dx mov dx,271h mov al,0 out dx,al mov dx,272h in al,dx and al,00000011B cmp al,00000011B jz no_key in al,dx and al,00000011B cmp al,00000011B jz no_key mov ah,0feh mov cx,8 next: mov al,ah rol ah,1 mov dx,271h out dx,al mov dx,272h in al,dx and al,03H cmp al,03H loopz next jz no_key ror ah,1 jmp exit no_key: mov ax,-1 exit: pop dx pop cx ret scankey endp translate proc push cx mov cx,16 lea si,segtab-1 lea di,keycode-2 scantab:inc si inc di inc di cmp ax,[di] loopnz scantab mov dl,[si] pop cx ret translate endp led_disp proc push bx push ax mov bl,dl mov al,0ffh mov dx,271h out dx,al mov al,bl mov dx,270h out dx,al mov al,0h mov dx,271h out dx,al pop ax pop bx ret led_disp endp end start
