LD	(STKEND),HL
		LD	A,+38	Initialise the colour system
		LD	(ATTR-P),A	variables to : FLASH 0,
		LD	(ATTR-T),A	BRIGHT 0, PAPER 7, & INK 0.
		LD	(BORDCR),A
		LD	HL,+0523	Initialise the system
		LD	(REPDEL),HL	variables REPDEL & REPPER.
		DEC	(KSTATE-0)	Make KSTATE-0 hold +FF
		DEC	(KSTATE-4)	Make KSTATE-4 hold +FF
		LD	HL,+15C6	Next move the initial stream
		LD	DE,+5C10	data from its table to the
		LD	BC,+000E	streams area.
		LDIR
		SET	1,(FLAGS)	Signal 'printer in use'
		CALL	0EDF,CLEAR-PRB	and clear the printer buffer.
		LD	(DF-SZ),+02	Set the size of the lower
		CALL	0D6B,CLS	part of the display and clear
				the whole display.
		XOR	A	Now print the message
		LD	DE,+1538	'(C) 1982 Sinclair Research Ltd'
		CALL	0C0A,PO-MSG	on the bottom line.
		SET	5,(TV-FLAG)	Signal 'the lower part will
				required to be cleared.
		JR	12A9,MAIN-1	Jump forward into the main
				execution loop.

THE 'MAIN EXECUTION' LOOP
The main loop extends from location 12A2 to location 15AE and it controls the 'editing mode', the execution of direct commands and the production of reports.

12A2	MAIN-EXEC	LD	(DF-SZ),+02	The lower part of the screen
				is to be two lines in size.
		CALL	1795,AUTO-LIST	Produce an automatic listing.
12A9	MAIN-1	CALL	16B0,SET-MIN	All the areas from E-LINE
				onwards are given their
				minimum configurations.

12AC	MAIN-2	LD	A,+00	Channel 'K' is opened before
		CALL	1601,CHAN-OPEN	calling the EDITOR.
		CALL	0F2C,EDITOR	The EDITOR is called to allow
				the user to build up a BASIC line.
		CALL	1B17,LINE-SCAN	The current line is scanned for
				correct syntax.
		BIT	7,(ERR-NR)	Jump forward if the syntax is
		JR	NZ,12CF,MAIN-3	correct.
		BIT	4,(FLAGS2)	Jump forward if other than
		JR	Z,1303,MAIN-4	channel 'K' is being used.
		LD	HL,(E-LINE)	Point to the start of the line
				with the error.
		CALL	11A7,REMOVE-FP	Remove the floating-point
				forms from this line.
		LD	(ERR-NR),+FF	Reset ERR-NR and jump back
		JR	12AC,MAIN-2	to MAIN-2 leaving the listing
				unchanged.

The 'edit-line' has passed syntax and the three types of line that are possible have to be distinguished from each other.

12CF	MAIN-3	LD	HL,(E-LINE)	Point to the start of the line.
		LD	(CH-ADD),HL	Set CH-ADD to the start also.
		CALL	19FB,E-LINE-NO	Fetch any line number into BC.
		LD	A,B	Is the line number a valid
		OR	C	one?
		JR	NZ,155D,MAIN-ADD	Jump if it is so, and add the new
				line to the existing program.