A bus filter includes a first bus interface connected to a system bus for receiving a virtual memory address and a second interface connected to the system bus for transmitting a physical memory address. In operation, an address translation unit, such as a translation lookaside buffer, determines the physical memory address from the virtual memory address. The bus filter may be used to couple a processing device, such as an accelerator, to a system having a core processor and an external memory unit coupled by a bus.