JTAG
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JTAG is an integrated method for testing interconnects on printed circuit boards (PCBs) that are implemented at the integrated circuit (IC) level. Since its introduction as an industry standard in 1990, JTAG has continuously grown in adoption, popularity, and usefulness—even today, new revisions and supplements to the IEEE Std.-1149.1 standard are being developed and implemented. This document is a brief introduction to the nature and history of JTAG, from its introduction to new extensions in current development.