【汇编语言与微机原理】实验五：键盘按键与数码管显示_微机原理键盘输入与显示实验

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
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