Hello Paul,

Here is the program to solve your problem but since you didn't include comments I won't either.

Regards,

Charles Bannister

	org	0
	ljmp	X8100		
	org	8100h
X8100:	mov	tmod,#1		
X8103:	jnb	p1.6,X8103	
X8106:	jb	p1.6,X8106	
X8109:	clr	24h.0		
	setb	p1.7		
	acall	X8116		
	clr	p1.7		
	jb	24h.0,X8109	
	sjmp	X8103		
X8116:	mov	r7,#64h		
X8118:	mov	th0,#0d8h	
	mov	tl0,#0f0h	
	setb	tr0		
X8120:	jb	p1.6,X8125	
	setb	24h.0		
X8125:	jnb	tf0,X8120	
	clr	tf0		
	clr	tr0		
	djnz	r7,X8118	
	ret			
	end