Background/objectives: Built in Self Test Architectures are used for the online or offline testing of the digital circuits and can be operated both in normal as well as test mode. So the objective is to test the circuit under test in online mode with less concurrent test latency and less area overhead. Methods/Statistical Analysis: In the case of normal mode the time required for testing becomes undesirable parameter so here we prefer offline testing method with concurrent approach which is also monitoring the window at the input by applying input vectors considering circuit under test as most important part of the processor which is arithmetic logic unit. Findings: The particular locations of the input vectors are stored in the latches which worked as the memory elements and this proposed scheme becomes more efficient by using cellular automata as test pattern generation and response analyzer using rule 90. Application/Improvement: The proposed scheme is comparable with the same architecture, considering TPG as LFSR (Linear Feedback Shift Register) and counter.