xin:	ld	hl,0		; ANSWER := 0;
xinloop:call	get		; A :== INPUT [character];
	cp	'0'		; is A LT '0'?
	ret	c		; if so then return;
	cp	':'		; is A LT ':' [numerics]?
	jp	c,xinshift	; if so then go shift it in;
	cp	'A'		; is A LT 'A'?
	ret	c		; if so then return;
	cp	'G'		; is A LT'G' [alphabetic A to F]?
	ret	nc		; if not then return;
	add	a,9		; A := A + 9 [convert to hexadecimal];
xinshift:
	and	15		; A := A & b'00001111' [mask low order];
	add	hl,hl		; shift ANSWER register pair
	ret	c		;     left four bit
	add	hl,hl		;     positions using
	ret	c		;     double byte addition
	add	hl,hl		;     and test each
	ret	c		;     operation for
	add	hl,hl		;     an overflow error
	ret	c		;     return condition;
	or	l		; A := A OR L [add new code to lower order];
	ld	l,a		; restore low order to ANSWER;
	jp	xinloop		; reiterate for next nybble;