实验内容：键盘采用4X4键盘，每个数码管显示值可为0-F共16个数。通过按键，求取键值0-F在R5寄存器中。通过按键，编写程序扫描键盘输入，并将扫描结果送数码管显示。实现对应不同按键在数码管上显示相应键值0-F的功能。

参考程序：

ORG 0000H

LJMP MAIN

ORG 0030H

MAIN:

MOV R1,#7AH

MOV R2,#06H

MOV A,#00H

L01:MOV @R1,A

INC R1

DJNZ R2,L01

LCALL DIR6

MA1:LCALL KEY

MOV A,R5

MOV R1,#7AH

MOV R2,#06H

L02:MOV @R1,A

INC R1

DJNZ R2,L02

LCALL DIR6

NOP

SJMP MA1

KEY: MOV DPTR,#7F03H

MOV A,#81H

MOVX @DPTR,A

MOV R4,#00H

MOV R2,#0FEH

KEY1:MOV DPTR,#7F00H

MOV A,R2

MOVX @DPTR,A

MOV DPTR,#7F02H

MOVX A,@DPTR

JB ACC.0,KEY2

MOV A,#00H

AJMP KEY5

KEY2:JB ACC.1,KEY3

MOV A,#01H

AJMP KEY5

KEY3:JB ACC.2,KEY4

MOV A,#02H

AJMP KEY5

KEY4:JB ACC.3,NEXT

MOV A,#03H

KEY5:ADD A,R4

MOV R4,A

MOV R5,A

RET

NEXT:MOV A,R4

ADD A,#04H

MOV R4,A

MOV A,R2

JNB ACC.3,NEXT1

RL A

MOV R2,A

AJMP KEY1

NEXT1:RET

DIR6:MOV R0,#7AH

MOV R3,#0FEH

MOV A,R3

DISP1:MOV DPTR,#7F00H

MOVX @DPTR,A

INC DPTR

MOV A,@R0

ADD A,#0DH

MOVC A,@A+PC

MOVX @DPTR,A

ACALL DELAY

INC R0

MOV A,R3

JNB ACC.5,DISP2

RL A

MOV R3,A

AJMP DISP1

DISP2:RET

SEGPT:DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH,77H,7CH,39H,5EH,79H,71H,73H

DELAY:MOV R5,#08H

DELAY1:MOV R4,#0FFH

DELAY2:DJNZ R4,DELAY2

DJNZ R5,DELAY1

RET

END