Managing complex boundary-scan operations

The IEEE 1149.1 Standard for Test Access Port and Boundary-Scan Architecture was approved and released in 1990. Since that time, there have been two supplements and one revision to the standard. A second revision is currently in process. The 1149.1 standard was originally developed to address board level test access issues while at the same time enabling access to test logic inside the device. As technology has scaled over the last 20+ years, component and board level density and complexity have grown significantly. A new class of defects (Timing, Power, Signal Integrity) has also become more prevalent and much more difficult to detect.