Abstract: An arbiter uses a history based bus arbitration scheme to more fairly allocate a shared resource among multiple devices. The arbiter uses a history queue to dynamically update the priorities of the devices using the shared resource, and makes the grant decision in a single calculation using the combination of the history queue and requests from bidding devices. The priority for granting master to each device is dynamically modified so that the least recently serviced requestor will be granted the shared resource. A hidden arbitration scheme provides more fair history based resource allocation. A bus retry scheme demotes priority for processing devices that are assigned bus master but do not perform bus operations within a predetermined number of clock cycles. The arbiter also prevents bus grants during hot swap operations.

Abstract: A memory control system and method for controlling access to a global memory. The global memory has multiple memory banks coupled to a memory bus. Multiple memory controllers are coupled between processing devices and the memory bus. The memory controllers control access of the processing devices to the multiple memory banks by independently monitoring the memory bus with each memory controller. The memory controllers track which processing devices are currently accessing which memory banks. The memory controllers overlap bus transactions for idle memory banks. The bus transactions include a control bus cycle that initially activates the target memory bank and data bus cycles that transfer data for previously activated memory banks.