求好心人指导 一生平安

ORG 0000H
LJMP STARTORG 000BH
AJMP TIME0 总是提示我 undefined symbol 为什么啊？
ORG 30H
START:MOV R0,#00H
MOV 30H,#00H
MOV TMOD,#01H
MOV TH0,#3CH
MOV TL0,#0B0H
SETB EA
SETB ET0
SETB TR0
SJMP $
TIME0：
PUSH ACC
PUSH PSW
INC 30H
MOV A,30H
CJNE A,#20,TIME1
INC R0
MOV 30H,#0
TIME1：MOV TH0,#3CH
MOV TL0,#0B0H
POP PSW
POP ACC
RETI
END