Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Nexus or IEEE-ISTO 5001-2003 is a standard debugging interface for embedded systems.The IEEE-ISTO 5001-2003 (Nexus) feature set is modeled on today''s on-chip debug implementations, most of which are processor-specific. Its goal is to create a rich debug feature set while minimizing the required pin-count and die area, and being both processor- and architecture independent. It also supports multi-core and multi-processor designs. Accordingly, it is comparable to the ARM CoreSight debug architecture.