1. A memory card, comprising: a card housing which houses a non-volatile memory and controller circuitry; and a first external connector corresponding to a first signal interface and a second external connector corresponding to second signal interface, said first and second external connectors enabling multiple host systems to connect to and use the memory card simultaneously using different respective bus structures; wherein the controller circuitry is capable concurrently receiving memory access commands via the first and second external connectors using the first and second bus structures, and is additionally capable of prioritizing the received memory access commands such that memory access commands received via one of the two external connectors are given priority over memory access commands received via the other external connector.