The Boundary-Scan handbook

Boundary-Scan, formally known as IEEE/ANSI Standard 1149.1-1990 is a collection of design rules applied principally at the Integrated Circuit (IC) level that allow software to alleviate the growing cost of designing, producing and testing digital systems. A fundamental benefit of the standard is its ability to transform extremely difficult printed circuit board testing problems that could only be attacked with Ad-Hoc testing methods into well-structured problems that software can easily deal with.

IEEE standards, when embraced by practicing engineers, are living entities that grow and change quickly. The Boundary-Scan Handbook, Second Edition: Analog and Digital is intended to describe these standards in simple English rather than the strict and pedantic legalese encountered in the standards.