177C		DEFB	53 08	- channel 'S', offset +08, address 1785
177E		DEFB	50 0A	- channel 'P', offset +0A, address 1789
1780		DEFB	00	- end marker;

THE 'OPEN-K' SUBROUTINE

1781	OPEN-K	LD	E,+01	The data bytes will be +01
		JR	178B,OPEN-END	& +00.

THE 'OPEN-S' SUBROUTINE

1785	OPEN-S	LD	E,+06	The data bytes will be +06
		JR	178B,OPEN-END	& +00.

THE 'OPEN-P' SUBROUTINE

1789	OPEN-P	LD	E,+10	The data bytes will be +10
				& +00.
178B	OPEN-END	DEC	BC	Decrease the length of the
		LD	A,B	expression and give an error
		OR	C	if it was not a single
		JR	NZ,1765,REPORT-F	character; otherwise clear the
		LD	D,A	D register, fetch HL and
		POP	HL	return.
		RET

THE 'CAT, ERASE, FORMAT & MOVE' COMMAND ROUTINES
In the standard SPECTRUM system the use of these commands leads to the production of report O - Invalid stream.

1793	CAT-ETC.	JR	1725,REPORT-O	Give this report.

THE 'LIST & LLIST' COMMAND ROUTINES
The routines in this part of the 16K program are used to produce listings of the current BASIC program.  Each line has to have its line number evaluated, its tokens expanded and the appropriate cursors positioned.
The entry point AUTO-LIST is used by both the MAIN EXECUTION routine and the EDITOR to produce a single page of the listing.

1795	AUTO-LIST	LD	(LIST-SP),SP	The stack pointer is saved
				allowing the machine stack to
				be reset when the listing is
				finished.  (see PO-SCR,0C55)
		LD	(TV-FLAG),+10	Signal 'automatic listing in the
				main screen'.
		CALL	0DAF,CL-ALL	Clear this part of the screen.
		SET	0,(FLAGS)	Switch to the editing area.
		LD	B,(DF-SZ)	Now clear the the lower part
		CALL	0E44,CL-LINE	of the screen as well.
		RES	0,(FLAGS)	Then switch back.
		SET	0,(FLAGS2)	Signal 'screen is clear'.
		LD	HL,(E-PPC)	Now fetch the the 'current' line
		LD	DE,(S-TOP)	number and the 'automatic'
				line number.
		AND	A	If the 'current' number is
		SBC	HL,DE	less than the 'automatic'
		ADD	HL,DE	number then jump forward to
		JE	C,17E1,AUTO-L-2	update the 'automatic' number.

The 'automatic' number has now to be altered to give a listing with the 'current' line appearing near the bottom of the screen.

		PUSH	DE	Save the 'automatic' number.
		CALL	196E,LINE-ADDR	Find the address of the
		LD	DE,+02C0	start of the 'current' line
		EX	DE,HL	and produce an address roughly