JR	NZ,1BEC,REPORT-N	check the validity of the state-
				ment number - must be zero.
		LD	B,A	Also check that the 'first
		LD	A,(HL)	line after' is not after the
		AND	+C0	actual 'end of program'.
		LD	A,B
		JR	Z,1BBF,LINE-USE	Jump forward with valid
				addresses; otherwise signal the
				error 'OK'.
Report 0 - 'OK'

1BB0	REPORT-0	RST	0008,ERROR-1	Use the error handling
		DEFB	+FF	routine.

Note: Obviously not an error in the normal sense — but rather a jump past the program.


THE 'REM' COMMAND ROUTINE
The return address to STMT-RET is dropped which has the effect of forcing the rest of the line to be ignored.

1BB2	REM	POP	BC	Drop the address - STMT-RET.

THE 'LINE-END' ROUTINE
If checking syntax a simple return is made but when 'running' the address held by NXTLIN has to be checked before it can be used.

1BB3	LINE-END	CALL	2530,SYNTAX-Z	Return if syntax is being
		RET	Z	checked; otherwise fetch
		LD	HL,(NXTLIN)	the address in NXTLIN.
		LD	A,+C0	Return also if the address is
		AND	(HL)	after the end of the program
		RET	NZ	- the'run' is finished.
		XOR	A	Signal 'statement zero' before
				proceeding.

THE 'LINE-USE' ROUTINE
This short routine has three functions; i. Change statement zero to statement '1'; ii. Find the number of the new line and enter it into PPC; & iii. Form the address of the start of the line after.

1BBF	LINE-USE	CP	+01	Statement zero becomes
		ADC	A,+00	statement '1'
		LD	D,(HL)	The line number of the line
		INC	HL	to be used is collected and
		LD	E,(HL)	passed to PPC.
		LD	(PPC),DE
		INC	HL	Now find the 'length'
		LD	E,(HL)	of the line.
		INC	HL
		LD	D,(HL)
		EX	DE,HL	Switch over the values.
		ADD	HL,DE	Form the address of the start
		INC	HL	of the line after in HL and the
				location before the 'next' line's
				first character in DE.

THE 'NEXT-LINE' ROUTINE
On entry the HL register pair points to the location after the end of the 'next' line to be handled and the DE register pair to the location before the first character of the line. This applies to lines in the program area and also to a line in the editing area - where the next line will be the same line again whilst there are still statements to be interpreted.

1BD1	NEXT-LINE	LD	(NXTLIN),HL	Set NXTLIN for use once the
				current line has been completed.
		EX	DE,HL	As usual CH-ADD points to the