Negate Binary Coded Decimal with extend

NAME
	NBCD -- Negate binary coded decimal with extend

SYNOPSIS
	NBCD	<ea>

	Size = (Byte)

FUNCTION
	The specified BCD number and the extend bit are subtracted
	from zero. Therefore, if the extend bit is set a nines
	complement is performed, else a tens complement is performed.
	The result is placed back in the specified <ea>.

	It can be useful to set the zero flag before performing
	this operation so that multi precision operations can
	be correctly tested for zero.

FORMAT
	-----------------------------------------------------------------
	|15 |14 |13 |12 |11 |10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
	|---|---|---|---|---|---|---|---|---|---|-----------|-----------|
	| 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |    MODE   | REGISTER  |
	----------------------------------------=========================
	                                                   <ea>

RESULT
	X - Set the same as the carry bit.
	N - Undefined.
	Z - Cleared it the result is non-zero, unchanged otherwise.
	V - Undefined.
	C - Set if a borrow was generated, cleared otherwise.

SEE ALSO
	NEG NEGX