Abstract: The cartridge has a memory for containing an information set, a status flag and a buffer for receiving an update to the information set, the update representing a change to only a part of the information set, and a data and power connector for connecting the cartridge to a host computer, the connector being able to receive power from the host computer and exchange data when connected to the host computer. The cartridge includes a power supply election switch including a battery for selectively supplying power from the host computer when the connector is connected and from the battery when disconnected. The update is transferred to the buffer and subsequently from the buffer to the information set in response to the status flag, such that in the event of a disconnection, while the update is being received, the information set is not partially updated.