mov	IEN0,#0		;disable all INTs
		jmp	prog

		org	100h
error:		jmp	$		;to signal ERROR/INT, if I get it anyway

prog:		mov	a,CKCON0	;is X2 on?
		jb	acc.0, error

		mov	a,CKRL		;clock prescaler?
		cjne	a, #0FFh, error

loop:		clr	P2.3
		acall	delay

		setb	P2.3
		acall	delay

		jmp	loop

delay:		mov	r1,0
		acall	delayMS
		mov	r1,0
		acall	delayMS
		mov	r1,0
		acall	delayMS
		mov	r1,0
		acall	delayMS
		mov	r1,0
		acall	delayMS
		mov	r1,0
		acall	delayMS
		ret

delayMS:	mov	r2,#26

dms1:		mov	r3,#32

		djnz	r3,$

		djnz	r2,dms1

		djnz	r1,delayMS
		ret