0C55	PO-SCR	BIT	1,(FLAGS)	Return immediately if the
		RET	NZ	printer is being used.
		LD	DE,+0DD9	Pre-load the machine stack
		PUSH	DE	with the address of 'CL-SET'.
		LD	A,B	Transfer the line number.
		BIT	0,(TV-FLAG)	Jump forward if considering
		JP	NZ,0D02,PO-SCR-4	'INPUT ... AT ..'.
		CP	(DF-SZ)	Return, via CL-SET, if the line
		JR	C,0C86,REPORT-6	number is greater than the value
		RET	NZ	of DF-SZ; give report 5 if it is
				less; otherwise continue.
		BIT	4,(TV-FLAG)	Jump forward unless dealing
		JR	Z,0C88,PO-SCR-2	with an 'automatic listing'.
		LD	E,(BREG)	Fetch the line counter.
		DEC	E	Decrease this counter.
		JR	Z,0CD2,PO-SCR-3	Jump forward if the listing
				is to be scrolled.
		LD	A,+00	Otherwise open channel 'K',
		CALL	1601,CHAN-OPEN	restore the stack pointer,
		LD	SP,(LIST-SP)	flag that the automatic
		RES	4,(TV-FLAG)	listing has finished and
		RET		return via CL-SET.

Report 5 - Out of screen

0C86 REPORT-S	RST	0008,ERROR-1	Call the error handling
		DEFB	+04	routine.

Now consider if the prompt 'scroll?' is required.

0C88	PO-SCR-2	DEC	(SCR-CT)	Decrease the scroll counter
		JR	NZ,0CD2,PO-SCR-3	and proceed to give the prompt
				only if is becomes zero.

Proceed to give the prompt message.

		LD	A,+18	The counter is reset.
		SUB	B
		LD	(SCR-CT),A
		LD	HL,(ATTR-T)	The current values of ATTR-T
		PUSH	HL	and MASK-T are saved.
		LD	A,(P-FLAG)	The current value of P-FLAG
		PUSH	AF	is saved.
		LD	A,+FD	Channel 'K' is opened.
		CALL	1601,CHAN-OPEN
		XOR	A	The message 'scroll?' is
		LD	DE,+0CF8	message '0'. This message is
		CALL	0C0A,PO-MSG	now printed.
		SET	5,(TV-FLAG)	Signal 'clear the lower screen
				after a keystroke'.
		LD	HL,+5C3B	This is FLAGS.
		SET	3,(HL)	Signal 'L mode'.
		RES	5,(HL)	Signal 'no key yet'.
		EXX		Note: DE should be pushed also.
		CALL	15D4,WAIT-KEY	Fetch a single key code.
		EXX		Restore the registers.
		CP	+20	There is a jump forward to
		JR	Z,0D00,REPORT-D	REPORT-D - 'BREAK - CONT
		CP	+E2	repeats' - if the keystroke
		JR	Z,0D00,REPORT-D	was 'BREAK', 'STOP', 'N' or
		OR	+20	'n'; otherwise accept the
		CP	+6E	keystroke as indicating the
		JR	Z,0D00,REPORT-D	need to scroll the display.
		LD	A,+FE	Open channel 'S'.
		CALL	1601,CHAN-OPEN
		POP	AF	Restore the value of