我是剛學不久的菜鳥，在做一個例子時出了問題，還望高手指點，謝謝
ORG 0000H
LJMP START
ORG 0030H

START:
CLR P0.4
ACALL DELAY
SETB P0.4
ACALL DELAY
AJMP START

DELAY:
MOV R7,#255
Y1:
MOV R6,#255
DJNZ R6,$
DJNZ R7,Y1
RET
END

可總是在引腳處報錯
BASS.ASM(5): error A45: UNDEFINED SYMBOL
BASS.ASM(7): error A45: UNDEFINED SYMBOL

用的芯片是philips 的P89C669