Methods and apparatus for adding an autonomous controller to an existing architecture such as by way of example, portable devices such as cell phones, MP3 players, and digital cameras. A circuit interposed between the memory card and the system controller of the device is controllable to couple the memory card to the system controller, or to couple the memory card to a high speed I/O controller on the circuit. When the memory card is coupled to the high speed I/O controller on the circuit, the circuit provides signals to the system controller indicative of a memory card removal event. In systems having an I/O connection such as a USB connection, the circuit also disconnects that connection from the system controller, provides signals to the system control indicative of a USB disconnect and connects the I/O connection to the memory card through a high speed data transfer unit to provide a higher speed I/O capability. Various features and capabilities are disclosed.