3501	NOT	CALL	34E9,TEST-ZERO	The carry flag will be set only if
				the 'last value' is zero; this gives
				the correct result.
	JR	350B,FP-0/1	Jump forward.

THE 'LESS THAN ZERO' OPERATION
(Offset 36: 'less-0')

This subroutine returns a 'last value'of one if the present 'last value' is less than zero and zero otherwise. It is also used by other subroutines to 'jump on minus'.

3506	less-0	XOR	A	Clear the A register.
3507	SIGN-TO-C	INC	HL	Point to the sign byte.
		XOR	(HL)	The carry is reset for a positive
		DEC	HL	number and set for a negative
		RLCA		number; when entered from
				GREATER-0 the opposite sign
				goes to the carry.


THE 'ZERO OR ONE' SUBROUTINE
This subroutine sets the 'last value' to zero if the carry flag is reset and to one if it is set. When called from 'E-TO-FP' however it creates the zero or one not on the stack but in mem-0.

350B	FP-0/1	PUSH	HL	Save the result pointer.
		LD	A,+00	Clear A without disturbing the
				carry.
		LD	(HL),A	Set the first byte to zero.
		INC	HL	Point to the second byte.
		LD	(HL),A	Set the second byte to zero.
		INC	HL	Point to the third byte.
		RLA		Rotate the carry into A, making
				A one if the carry was set, but
				zero if the carry was reset.
		LD	(HL),A	Set the third byte to one or
				zero.
		RRA		Ensure that A is zero again.
		INC	HL	Point to the fourth byte.
		LD	(HL),A	Set the fourth byte to zero.
		INC	HL	Point to the fifth byte.
		LD	(HL),A	Set the fifth byte to zero.
		POP	HL	Restore the result pointer.
		RET		


THE 'OR' OPERATION
(Offset 07: 'or')

This subroutine performs the binary operation 'X OR Y' and returns X if Y is zero and the value 1 otherwise.

351B	or	EX	DE,HL	Point HL at Y, the second
				number.
		CALL	34E9,TEST-ZERO	Test whether Y is zero.
		EX	DE,HL	Restore the pointers.
		RET	C	Return if Y was zero; X is now
				the 'last value'.
		SCF		Set the carry flag and jump back
		JR	350B,FP-0/1	to set the 'last value' to 1.

THE 'NUMBER AND NUMBER' OPERATION
(Offset 08: 'no-&-no')

This subroutine performs the binary operation 'X AND Y' and returns X if Y is non-zero and the value zero otherwise.