A patellar prosthesis used to replace a portion of the natural knee. For example, command processing systems and methods are provided which can automatically determine, evaluate or otherwise predict consequences of execution of misrecognized or misinterpreted user commands in automated systems and thus prevent undesirable or dangerous consequences that can result from execution of misrecognizedmisinterpreted commands. These tests are validated to determine whether they cause errors within the SUT. In this configuration, a user may quickly and easily actuate the clip assembly to release or engage the inlet conduit assembly. To provide quick transition from read mode to write mode, the writer circuitry is transitioned to a pre-write mode before the end of the read operation. As a result, it can maintain a good water quality and is energy efficient.