Unisys Corporation

Ross M Weber

Kelvin S Vartti

Mitchell A Bauman

Ronald G Arnold

David R Spatafore

Chad M Sepeda

Control logic of a node controller receives an input vector and produces an output vector. The control logic includes a plurality of tied control store entries including hard-coded logic to identify unique values of the input vector and to produce the output vector from a hard-coded output vector when the input vector is identified and when the tied control store is enabled. The control logic also includes a plurality of spare control store entries including programmable logic configurable to identify values of the input vector and to produce the output vector from a programmable output vector when the input vector is identified and when the spare control store is enabled. One of the spare control store entries that is configured to identify a value of the input vector that none of the tied control store entries that are enabled by the entry-enables register are configured to identify is enabled.

Logic controller having hard-coded control logic and programmable override control store entries

A system and method are provided for tracking memory requests within a data processing system. The system includes a request tracking circuit that is coupled to receive requests for data from multiple processors. Multiple pending requests to the same memory address are tracked using a linked list. Only the oldest pending one of these multiple requests is issued to the memory. When data is returned from the memory, the requests are processed in an order determined by the linked list. That is, the data is provided to a processor associated with the oldest request. Thereafter, the data is retrieved and provided to the processor associated with the next request, and so on. A request issued by the memory soliciting the return of the data to the memory may also be added to the linked list to be processed in the foregoing manner.

System and method for handling memory requests in a multiprocessor shared memory system

A memory control system and method is disclosed. The system includes cache tag logic and an optional cache coupled to a main memory. If available, the cache retains a subset of the data stored within the main memory. This subset is selected by programmable control indicators. These indicators further control which data will be recorded by the tag logic. The indicators may select the sub-sets based on which type of memory request results in the return of data from the main memory to the cache, for example. Alternatively, or in addition, these indicators may specify the identity of a requester, a memory response type, or a storage mode to control the selection of the sub-sets of data stored within the cache and recorded by the tag logic. In one embodiment, data may be tracked by the cache tag logic but not stored within the cache itself.

Programmable cache management system and method

A system and method for arbitrating for access to a resource group between agents according to a respective programmable weight for each agent. For each agent, a programmable mapping module selectively couples a respective arbitration handshake signal of the agent to one or more arbitration ports, and the number of the coupled arbitration ports for the agent is the respective programmable weight. A selection module selects one of the arbitration ports in response to a priority ranking of the arbitration ports, and access to the resource group is granted to the agent that has the respective arbitration handshake signal that is selectively coupled by the programmable mapping module to the selected arbitration port. A ranking module provides the priority ranking of the arbitration ports and updates the priority ranking in response to the selection module selecting the selected arbitration port.

Apparatus and method for arbitrating for a resource group with programmable weights

A memory control system and method is disclosed. In one embodiment, a first memory is coupled to one or more additional memories. The first memory receives requests for data that are completed by retrieving the data from the first memory and/or the one or more additional memories. The manner in which this data is retrieved is determined by the state of programmable control indicators. In one mode of operation, a reference is made to the first memory to retrieve the data. If it is later determined from tag information stored by the first memory that the one or more additional memories must be accessed to fulfill the request, the necessary additional memory references are initiated. In another mode of operation, references to the one or more additional memories are initiated irrespective of whether these references are required. The operating mode may be selected to optimize system efficiency.

Programmable system and method for accessing a shared memory

A dual-channel memory system and accompanying coherency mechanism is disclosed. The memory includes both a request and a response channel. The memory provides data to a requester such as an instruction processor via the response channel. If this data is provided for update purposes, other read-only copies of the data must be invalidated. This invalidation may occur after the data is provided for update purposes, and is accomplished by issuing one or more invalidation requests via one of the memory request or the response channel. Memory coherency is maintained by preventing a requester from storing any data back to memory until all invalidation activities that may be directly or indirectly associated with that data have been completed.

Growing community of inventors

Coon Rapids, MN, United States of America

Ross M Weber