ASCTOBCD:
MOV 	R7,# 06H
MOV 	R1,# 20H				
MOV 	R0,#20H				
ACALL 	ASCBCD
LOOP:
SJMP 	LOOP
ASCBCD:
MOV	A,@R0
CLR 	C
CJNE 	A,#30H,LOOP1
LOOP1:						
JC 		C, LOOP3
CJNE 	A,#3AH,LOOP2
LOOP2:
JNC 		C, LOOP4
CLR		C
SUBB	A, # 30H
LOOP3:
MOVX 	@R1,A.				
INC		R0
INC		R1
DJNZ	R7,ASCBCD
RET
LOOP4:
MOV 	A,#0FFH
MOVX 	@R1,A
LJMP 	LOOP3
RET