The paper reports current results in the design, implementation and applications of an IEEE 1149.4 test chip with extended ABM functionality. As no previous experience or information on Dot 4 compatible integrated circuits design was available, the project has been approached in two stages. A simplified preliminary test chip was designed "from scratch" and has recently become available. Debug and evaluation of the preliminary design will provide useful information for the design and implementation of a second test chip version. Besides correcting identified design deficiencies the second version will also include minor ABM modifications which will allow the development of enhanced measurement procedures as described in the paper.