IEEE-1149.x standards: achievements vs. expectations

This paper examines the IEEE-1149 standard and its .x sub standards. Since the JTAG/IEEE-1149.1 boundary-scan was first standardized in 1990, it has undergone some close scrutiny. The paper discusses how this pioneering standard met expectations, how it achieved some unplanned utilities, and what other surprises came to light. The paper also looks at the progress of some of the other standards that were published later. The IEEE-1149.5 system level testability standard was published in 1995, but has not gained as much popularity. The reasons are examined and information is provided on how the 1149.5 could be used more effectively. The IEEE-1149.4, released in November 1999, incorporates the features of the digital boundary-scan while adding analog capabilities. The other two assigned numbers, 1149.2 and 1149.3 never became standards. This paper reports on the present status and utility of the 1149.x standards with an eye to their future applications. It concludes that the standards meet the challenges brought about by greater complexities in electronics and indicates confidence that they will remain an integral part of the board and system level testability needs well into the foreseeable future.