西南交大微机与接口实验8255作键盘和数码管接口综合设计实验程序

要求用8255作为键盘和数码管接口。用行扫描法从试验台上小键盘的数字字母区读取‘0’-‘9’或‘A’-‘F’按键值,并显示在某数码管上。

8255作键盘和数码管接口综合设计实验：

实验要求：要求用8255作为键盘和数码管接口。用行扫描法从试验台上小键盘的数字字母区读取‘0’-‘9’或‘A’-‘F’按键值，并显示在某数码管上。

程序：

data segment

io8255a equ 288h

io8255b equ 289h

io8255c equ 28ah

io8255z equ 28bh

key db 37h,38h,39h,41h,54h,52h

db 34h,35h,36h,42h,53h,4dh

db 31h,32h,33h,43h,48h,4ch

db 30h,46h,45h,44h,58h,4eh

led1 db 3fh,06h,5bh,4fh,66h,6dh,7dh,07h,7fh,6fh

led2 db 77h,7ch,39h,5eh,79h,71h

data ends

code segment

assume cs:code,ds:data

start:

mov ax,data

mov ds,ax

lp0:

mov dx,io8255z

mov al,90h

out dx,al

lp1:mov di,0

mov si,0

mov ah,11111110b

mov cx,4

lp2:mov al,ah

mov dx,io8255c

out dx,al

mov dx,io8255a

in al,dx

and al,00111111b

cmp al,00111111b

jnz realy

rol ah,1

loop lp2

要求用8255作为键盘和数码管接口。用行扫描法从试验台上小键盘的数字字母区读取‘0’-‘9’或‘A’-‘F’按键值,并显示在某数码管上。

jmp lp1

realy:

push ax

mov dx,io8255a in al,dx

nop

nop

nop

nop

and al,3fh

cmp al,3fh

jnz realy

pop ax

l4: mov cx,6

lp4:shr al,1

jnc l3

inc si

loop lp4

l3: mov cx,4

mov al,ah lp3:shr al,1

jnc lp5

inc di

loop lp3

lp5:mov bx,di

mov al,6

mul bl

add ax,si

disp:

mov bx,offset key xlat

cmp al,39h jl ll

cmp al,40h jg lll

ll: sub al,30h

mov bx,offset led1

要求用8255作为键盘和数码管接口。用行扫描法从试验台上小键盘的数字字母区读取‘0’-‘9’或‘A’-‘F’按键值,并显示在某数码管上。

xlat

mov dx,io8255b out dx,al

jmp lp1

lll: sub al,41h

mov bx,offset led2 xlat

mov dx,io8255b out dx,al

jmp lp1

exit:

mov ah,4ch int 21h

delay proc near push cx

mov cx,20h l1: loop l1 pop cx

ret

delay endp

code ends

end start