Microcontroller program

1. ;Expt5:Matrix Keyboard interface to 8051
;Rows(1-4)=P1.0 to P1.3,Column(1-4)=P1.4 to P1.7
;P2= Output on 7 segment diaplay(0 to 9 and A to F)
Org 0000H
BACK: MOV DPTR,#Mydata // moves starting address of LUT to DPTR
MOV P1,#0FFH // loads P1 with all 1's
CLR P1.0 // makes row 1 low
JB P1.4,NEXT1 // checks whether column 1 is low and jumps to NEXT1 if not low
MOV A,#00H
ACALL DISPLAY // calls DISPLAY subroutine
NEXT1: JB P1.5,NEXT2 // checks whether column 2 is low and so on...
MOV A,#01H
ACALL DISPLAY
NEXT2: JB P1.6,NEXT3
MOV A,#02H
ACALL DISPLAY
NEXT3: JB P1.7,NEXT4
MOV A,#03H
ACALL DISPLAY
NEXT4: SETB P1.0
CLR P1.1 // makes row 2 low
JB P1.4,NEXT5
MOV A,#04H
ACALL DISPLAY
NEXT5: JB P1.5,NEXT6
MOV A,#05H
ACALL DISPLAY
NEXT6: JB P1.6,NEXT7
MOV A,#06H
ACALL DISPLAY
NEXT7: JB P1.7,NEXT8
MOV A,#07H
ACALL DISPLAY
NEXT8: SETB P1.1
CLR P1.2 // makes row 3 low
JB P1.4,NEXT9
MOV A,#08H
ACALL DISPLAY
NEXT9: JB P1.5,NEXT10
MOV A,#09H
ACALL DISPLAY
NEXT10:JB P1.6,NEXT11
MOV A,#0AH
ACALL DISPLAY
NEXT11:JB P1.7,NEXT12
MOV A,#0BH
ACALL DISPLAY

2. NEXT12:SETB P1.2
CLR P1.3 // makes row 4 low
JB P1.4,NEXT13
MOV A,#0CH
ACALL DISPLAY
NEXT13:JB P1.5,NEXT14
MOV A,#0DH
ACALL DISPLAY
NEXT14:JB P1.6,NEXT15
MOV A,#0EH
ACALL DISPLAY
NEXT15:JB P1.7,BACK
MOV A,#0FH
ACALL DISPLAY
LJMP BACK
DISPLAY:MOVC A,@A+DPTR
MOV P2,A
RET
ORG 500H
Mydata: DB 3FH, 06H, 5BH, 4FH
DB 66H, 6DH, 7DH, 07H
DB 7FH, 6FH, 77H, 7CH
DB 39H, 5EH, 79H, 71H
END