Image Number 6 for United States Patent #8015448.
A storage controller including a first controller. The first controller includes a memory module, a test access port controller, the test access port controller configured to control a built in self-test operation on the memory module, and a register configured to store a first instruction. In response to the storage controller detecting a test access port interface being accessible to the storage controller, the test access port controller is configured to control the built in self-test operation on the memory module of the first controller by having either (i) a second instruction sent from the test access port controller to the first controller or (ii) the first instruction sent from the register to the first controller. The first controller is configured to perform the built in self-test operation on the memory module in response to having received the first instruction or having received the second instruction.