Prior to the mid 1980s, the dominance of through-hole packaging of integrated circuits (ICs) provided easy access to nearly every pin of every chip on a printed circuit board. Providing accessibility and controllability for board testing was simply a matter of probing the board. With the advent of surface mount packaging, the accessibility for probing printed circuit boards began to diminish. Logic cores being integrated onto chips made them inaccessible as well. One of the solutions to address this problem eventually