A removable electronic circuit card has multiple modules connected to the card's bus in parallel so that each module can exchange commands and data independently with the host. According to a first aspect of the present invention, this achieved by a controller-to-controller interface whereby the modules can facilitate their interactions with the host. In a first set of embodiments, the modules are on a single card, while in a second set of embodiments the modules are distributed across multiple cards, where a first card attaches to the host and other cards attach to the first card rather than directly to the host. In all of these cases, the host sees the multiple modules as a single card having a single module. In a further aspect of the present invention, the card or cards are able to communicate with the host in more than one protocol.