Abstract: Management of access to shared resources within a system comprising a plurality of requesters and a plurality of target resources is provided. A separate arbitration point is associated with each target resource. An access priority value is assigned to each requester. An arbitration contest is performed for access to a first target resource by requests from two or more of the requesters using a first arbitration point associated with the first target resource to determine a winning requester. The request from the winning requester is forwarded to a second target resource. A second arbitration contest is performed for access to the second target resource by the forwarded request from the winning requester and requests from one or more of the plurality of requesters using a second arbitration point associated with the second target resource.

Abstract: This invention is a data processing system having a multi-level cache system. The multi-level cache system includes at least first level cache and a second level cache. Upon a cache miss in both the at least one first level cache and the second level cache the data processing system evicts and allocates a cache line within the second level cache. The data processing system determine from the miss address whether the request falls within a low half or a high half of the allocated cache line. The data processing system first requests data from external memory of the miss half cache line. Upon receipt data is supplied to the at least one first level cache and the CPU. The data processing system then requests data from external memory for the other half of the second level cache line.

Abstract: Management of access to shared resources within a system comprising a plurality of requesters and a plurality of target resources is provided. A separate arbitration point is associated with each target resource. An access priority value is assigned to each requester. An arbitration contest is performed for access to a first target resource by requests from two or more of the requesters using a first arbitration point associated with the first target resource to determine a winning requester. The request from the winning requester is forwarded to a second target resource. A second arbitration contest is performed for access to the second target resource by the forwarded request from the winning requester and requests from one or more of the plurality of requesters using a second arbitration point associated with the second target resource.

Abstract: This invention is a data processing system having a multi-level cache system. The multi-level cache system includes at least first level cache and a second level cache. Upon a cache miss in both the at least one first level cache and the second level cache the data processing system evicts and allocates a cache line within the second level cache. The data processing system determine from the miss address whether the request falls within a low half or a high half of the allocated cache line. The data processing system first requests data from external memory of the miss half cache line. Upon receipt data is supplied to the at least one first level cache and the CPU. The data processing system then requests data from external memory for the other half of the second level cache line.

Abstract: A second level memory controller uses shadow tags 711 to implement snoop read and write coherence. These shadow tags are generally used only for snoops intending to keep L2 SRAM coherent with the level one data cache. Thus updates for all external cache lines are ignored. The shadow tags are updated on all level one cache allocates and all dirty and invalidate modifications to data stored in L2 SRAM. These interactions happen on different interfaces, but the traffic on that interface includes level one data cache accesses to both external and level two directly addressable lines. These interactions create extra traffic on these interfaces and creating extra stalls to the CPU. Thus in this invention shadow tags are updated only on a subset of less than all updates of the level one tags.

Abstract: In a data processing system have a master-state data processing unit and at least one slave-state data processing unit, the data processing units can be provided with an asynchronous transfer mode interface unit for transferring data cells there between. The interface unit provides and receives signals formatted in the UTOPIA protocol. The interface unit includes processor acting as a state machine and a buffer out memory unit for buffering the data groups between the interface unit processor and the direct memory access unit of the data processing unit. The interface unit can act in a receive mode and a transmit mode for a master-state data processing unit and can act in a receive mode, and transmit mode in a slave-state data processing unit. An event signal provides an efficient exchange of transfer of data between the direct memory access unit and the buffer memory storage unit in the slave mode.