NAME ROWSCAN                          ;行掃描

KEY_ROW1	equ	0EFh
KEY_ROW2	equ	0DFh
KEY_ROW3	equ	0BFh
KEY_ROW4	equ	07Fh

ORG 0000H
				ljmp START
ORG 0100H		
START:			mov R0,#00 			
				mov R1,#KEY_ROW1	
				mov R2,#4			  ;行數

ksrow:			mov P1,R1			
				nop
				mov A,P1			
				mov R3,#4			  ;列數
				anl A,#0Fh
ks0:			rrc A
				
				jc ks1				  ;沒鍵按下
				jmp ksnew			  ;有鍵按下
			
ks1:			inc R0			
				djnz R3,ks0

				mov A,R1			
				rl A 
				mov R1,A
				djnz R2,ksrow
									   
				jmp ksend
			
ksnew:			mov DPTR,#keycodes				
				mov A,R0		
				movc A,@A+DPTR			
				mov P0,A
				nop
				nop
							
ksend:			ljmp START

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

				END