START EQU P3.1
RESET EQU P3.0
BUZZ EQU P3.7

DISA EQU P3.3
DISB EQU P3.2
DISC EQU P3.6

ORG 0000H
LJMP MAIN
ORG 0040H
MAIN:
	 CLR BUZZ
	 JB START,$					  	;WAIT FOR START BUTTON TO BE PRESSED
	 SETB DISA
	 SETB DISB
	 SETB DISC
DD1:SETB DISA
	MOV A,#09H						;SETTING FOR MINUTE
	MOV R1,A
	MOV R4,A
DS1:MOV P0,R1
	DD2:MOV A,#05H
	DS2:MOV P2,A
		DD3:MOV A,#09H
		DS3:MOV P1,A
			ACALL AAA
			DEC A
			CJNE A,#00H,DS3
		MOV A,P2
		MOV P1,#00H
		ACALL AAA
		DEC A
		CJNE A,#00H,DS2
TEN:MOV P2,#00H
	MOV R6,#09H
	TE:MOV P1,R6
	DEC	R6
	ACALL AAA
	CJNE R6,#00H,TE
	MOV P1,#00H
DEC R1
ACALL AAA
MOV P0,R1
CJNE R1,#00H,DS1
MOV P0,#00H
LASTMIN:
DE2:MOV A,#05H
	DF2:MOV P2,A
		DE3:MOV A,#09H
		DF3:MOV P1,A
			ACALL AAA
			DEC A
			CJNE A,#00H,DF3
		MOV A,P2
		MOV P1,#00H
		ACALL AAA
		DEC A
		CJNE A,#00H,DF2
LASTEN:
MOV P0,#00H
MOV P2,#00H
MOV R6,#09H
	TE1:MOV P1,R6
	DEC	R6
	ACALL AAA
	CJNE R6,#00H,TE1
	MOV P1,#00H
	SETB BUZZ
JB RESET,$						 ;END OF COUNTDOWN.WAIT FOR RESET TO BE PRESSED
MOV P0,R4
MOV P2,#05H
MOV P1,#09H
CLR BUZZ
JMP MAIN
AAA:
ACALL RST
ACALL STP
ACALL DELAY
ACALL RST
ACALL STP
RET
RST:						  	;RESETS ALL DISPLAYS AND RETURNS TO START
JB RESET,DOWN
MOV P0,R4
MOV P1,#09H
MOV P2,#05H
JMP MAIN
DOWN:RET
STP:							 ;PAUSE ROUTINE FOR TIMER
S1:JB START,DWN
SJMP S1
DWN:RET
DELAY:							 ;DELAY OF ONE SECOND
 		MOV TMOD,#01H
		MOV TH0,#3CH
		MOV TL0,#0B0H
		MOV R7,#00H
		SETB TR0
	DEL:JNB TF0,DEL
		MOV TH0,#3CH
		MOV TL0,#0B0H
		CLR TF0
		INC R7
		CJNE R7,#14H,DEL
		RET

END