Multiple data devices (A,B,C) are interfaced via a bus arbiter (S) with an external memory (F) so as to support burst-mode access by each device (A,B,C) one or more read registers (R1,R2,R3) are provided in the memory (F), and each register (R1,R2,R3) supports burst-mode access by a corresponding device (A,B,C). The arbiter (s) selects the register to be used following the initial access burst, according to the device requiring access. Thus, the memory (F) supports multiple burst-mode accesses in parallel.