A data flow control and bridging architecture that enhances the performance of removable data storage systems. In one implementation, the present invention provides a bypass bus implementation where the data transfer phase associated with select commands occurs directly between the host computing system and the target removable data storage unit. In one implementation, the present invention further provides a data flow and bridging architecture that emulates a removable media interface, such as the ATAPI interface, to the host computing system, and translates these commands for a target removable storage unit that implements a fixed media interface, such as the ATA interface. In yet another implementation, the present invention provides a data flow and bridging architecture that supports the serial ATA interface.