Editor's note:
AC-coupled high-speed differential signals have been a hole in the IEEE 1149.1 boundary-scan standard since its inception. In May 2001, a group formed to address this problem, resulting in the IEEE 1149.6 standard. Several members of the IEEE 1149.6 working group describe how the standard works and how it can test Gigabit Ethernet, Fibre Channel, and more.
—Rob Aitken, Artisan Components