Abstract: In an information processing system which has plurality of modules including a processor, a main memory and a plurality of I/O devices, a data transfer switch for performing data transfer operations between the processor, main memory and I/O devices comprises a request bus which has a request bus arbiter for receiving read and write requests from each one of the plurality of modules. A processor memory bus is configured to receive address and data information from a predetermined number of modules, including the processor. The processor memory bus has a data bus arbiter for receiving data read and write requests from each one of the predetermined number of modules which are coupled to the processor memory bus. An internal memory bus is configured to receive address and data information from a predetermined number of modules, including the memory and the I/O devices.