MIL-HDBK-528A provides guidance for the Department of Defense (DoD) to acquire avionics systems that use Boundary Scan. This document describes the design considerations necessary for a host system to implement Boundary Scan Diagnostics (BSD). Boundary Scan is a technique used to test the interconnections between integrated circuits (ICs) on a printed circuit boards (PCBs), as well as to test the health of the ICs themselves and to load data into them. Boundary Scan can also be used in a system-level configuration between several boards. Boundary Scan is low cost and requires less physical access to circuit components than traditional testing techniques, such as In-Circuit Testing (ICT) for detecting and isolating component failures. With today?s highly complex and dense circuit cards, Boundary Scan is a useful technique for troubleshooting and ensuring production quality.