Abstract: An integrated circuit includes one or more portions having error detection and error correction circuits and which is operated with operating parameters giving finite non-zero error rate as well as one or more portions formed and operated to provide a zero error rate.

Abstract: An integrated circuit includes one or more portions having error detection and error correction circuits and which is operated with operating parameters giving finite non-zero error rate as well as one or more portions formed and operated to provide a zero error rate.

Abstract: An interconnect within an integrated circuit provides arbitration to select one of a plurality of signal inputs for connection to a signal output. The arbitration applied uses a first arbitration parameter value, in the form of a time stamp value, and, if two or more signal inputs share such a time stamp value, then uses a second arbitration parameter, in the form of a least recently granted value. The time increment applied to the time stamp value associated with each signal input when it is granted access to the signal output is selected to reflect the quality of service to be associated with that signal input. When a comparison is made between time stamp values, the lowest time stamp value is given priority. A large time increment value corresponds to a low priority (quality of service).

Abstract: An interconnect within an integrated circuit provides arbitration to select one of a plurality of signal inputs for connection to a signal output. The arbitration applied uses a first arbitration parameter value, in the form of a time stamp value, and, if two or more signal inputs share such a time stamp value, then uses a second arbitration parameter, in the form of a least recently granted value. The time increment applied to the time stamp value associated with each signal input when it is granted access to the signal output is selected to reflect the quality of service to be associated with that signal input. When a comparison is made between time stamp values, the lowest time stamp value is given priority. A large time increment value corresponds to a low priority (quality of service).

Abstract: A hardware transactional memory 12, 14, 16, 18, 20 is provided within a multiprocessor 4, 6, 8, 10 system with coherency control and hardware transaction memory control circuitry 22 that serves to at least partially manage the scheduling of processing transactions in dependence upon conflict data 26, 28, 30. The conflict data characterizes previously encountered conflicts between processing transactions. The scheduling is performed such that a candidate processing transaction will not be scheduled if the conflict data indicates that one of the already running processing transactions has previously conflicted with the candidate processing transaction.

Abstract: A data processing apparatus has a memory rename table for storing memory rename entries each identifying a mapping between a memory address of a location in memory and a mapped register of a plurality of registers. The mapped register is identified by a register number. In response to a store instruction, the store target memory address of the store instruction is mapped to a store destination register and so the data value is stored to the store destination register instead of memory. A memory rename entry is provided in the table to identify the mapping between the store target memory address and store destination target register. In response to a load instruction, if there is a hit in the memory rename table for the load target memory address then the loaded value can be read from the mapped register instead of memory.

Abstract: An integrated circuit includes one or more portions having error detection and error correction circuits and which is operated with operating parameters giving finite non-zero error rate as well as one or more portions formed and operated to provide a zero error rate.

Abstract: An integrated circuit includes one or more portions having error detection and error correction circuits and which is operated with operating parameters giving finite non-zero error rate as well as one or more portions formed and operated to provide a zero error rate.

Abstract: A data processing system 2 is provided with branch prediction circuitry 20 for performing branch prediction operations. Next branch table circuitry 22 stores data identifying from a given branch instruction what will be the address of the next branch instruction to be encountered within the program flow. This next branch instruction address is supplied to the branch prediction circuitry 20 which uses it to form its prediction prior to that next branch instruction being identified as such by the instruction decoder 16. This permits branch prediction to commence earlier in the branch prediction circuitry 20 than would otherwise be the case.

Abstract: A hardware transactional memory is provided within a multiprocessor system with coherency control and hardware transaction memory control circuitry that serves to at least partially manage the scheduling of processing transactions in dependence upon conflict data. The conflict data characterizes previously encountered conflicts between processing transactions. The scheduling is performed such that a candidate processing transaction will not be scheduled if the conflict data indicates that one of the already running processing transactions has previously conflicted with the candidate processing transaction.

Abstract: A data processing apparatus has a memory rename table for storing memory rename entries each identifying a mapping between a memory address of a location in memory and a mapped register of a plurality of registers. The mapped register is identified by a register number. In response to a store instruction, the store target memory address of the store instruction is mapped to a store destination register and so the data value is stored to the store destination register instead of memory. A memory rename entry is provided in the table to identify the mapping between the store target memory address and store destination target register. In response to a load instruction, if there is a hit in the memory rename table for the load target memory address then the loaded value can be read from the mapped register instead of memory.

Abstract: Interconnect circuitry 2 has a plurality of data source circuits 8 connected to respective input paths 4 and a plurality of data destination circuits 10 connected to respective output paths 6. Connection cells 12 provide selective connections between input paths 4 and output paths 6. Arbitration circuitry 26 provides adaptive priority arbitration between overlapping requests received at different input paths. Priority bits 16 within a matrix of priority bit 46 for each output path 10 are used to represent the priority relationships between different input paths which compete for access to that output path 10. Update operations are applied on a per row or per column basis within the matrix to implement update schemes such as least recently granted, most recently granted, round robin, reversal, swap, selective least recently granted, selective most recently granted etc.

Abstract: An integrated circuit includes one or more portions having error detection and error correction circuits and which is operated with operating parameters giving finite non-zero error rate as well as one or more portions formed and operated to provide a zero error rate.

Abstract: An interconnect 6 within an integrated circuit 2 provides arbitration to select one of a plurality of signal inputs for connection to a signal output. The arbitration applied uses a first arbitration parameter value, in the form of a time stamp value, and, if two or more signal inputs share such a time stamp value, then uses a second arbitration parameter, in the form of a least recently granted value. The time increment applied to the time stamp value associated with each signal input when it is granted access to the signal output is selected to reflect the quality of service to be associated with that signal input. When a comparison is made between time stamp values, the lowest time stamp value is given priority. A large time increment value corresponds to a low priority (quality of service).

Abstract: A data processing system 2 is provided with branch prediction circuitry 20 for performing branch prediction operations. Next branch table circuitry 22 stores data identifying from a given branch instruction what will be the address of the next branch instruction to be encountered within the program flow. This next branch instruction address is supplied to the branch prediction circuitry 20 which uses it to form its prediction prior to that next branch instruction being identified as such by the instruction decoder 16. This permits branch prediction to commence earlier in the branch prediction circuitry 20 than would otherwise be the case.

Abstract: Crossbar circuitry has an array of data input and output paths where the data output paths are transverse to the data input paths. At each intersection between a data input path and a data output path, a crossbar cell is provided which includes a configuration storage circuit programmable to store a routing value, a transmission circuit, and an arbitration circuit. In a transmission mode of operation, the transmission circuit is responsive to the routing value being a first value, indicating that the data input path should be coupled to the data output path, to detect the data input along the data input path, and to output an indication of that data on the data output path at the associated intersection. In an arbitration mode of operation, the arbitration circuitry is operable to selectively modify the voltage on said plurality of bit lines in order to apply an adaptive priority scheme.

Abstract: An integrated circuit includes a plurality of processing stages each including processing logic 1014, a non-delayed signal-capture element 1016, a delayed signal-capture element 1018 and a comparator 1024. The non-delayed signal-capture element 1016 captures an output from the processing logic 1014 at a non-delayed capture time. At a later delayed capture time, the delayed signal-capture element 1018 also captures a value from the processing logic 1014. An error detection circuit 1026 and error correction circuit 1028 detect and correct random errors in the delayed value and supplies an error-checked delayed value to the comparator 1024. The comparator 1024 compares the error-checked delayed value and the non-delayed value and if they are not equal this indicates that the non-delayed value was captured too soon and should be replaced by the error-checked delayed value.

Abstract: A circuit for generating a random output value is disclosed that comprises: a bistable circuit having two stable states in which a 0 or a 1 is output and having a balanced metastable state in which a floating value between 0 and 1 is output, said bistable circuit resolving from said metastable state to one of said stable states on being switched on, said state depending on a voltage level at a port on said bistable circuit; a voltage level control circuit for controlling a voltage level at said port on said bistable circuit; a time measuring circuit for measuring a switching time taken for said bistable circuit to switch from said metastable state to one of said stable states following switch on; and control logic for controlling said time measuring circuit, said voltage level control circuit and a switching off and on of said bistable circuit, said control logic being adapted to perform a following sequence: control said voltage level control circuit to set a predetermined voltage level at said port on said

Abstract: A data processing apparatus is provided having a cache memory comprising a data storage array and a tag array and a cache controller coupled to the cache memory responsive to a cache access request from processing circuitry to perform cache look ups. The cache memory is arranged such that it has a first memory cell group configured to operate in a first voltage domain and a second memory cell group configured to operate in a second voltage domain that is different from the first voltage domain. A corresponding data processing method is also provided.

Abstract: A data processing apparatus 1 comprises data processing circuitry 2, a memory 8 for storing data and a cache memory 5 for storing cached data from the memory 8. The cache memory 5 is partitioned into cache segments 12 which may be individually placed in a power saving state by power supply circuitry 15 under control of power control circuitry 22. The number of segments which are active at any time may be dynamically adjusted in dependence upon operating requirements of the processor 2. An eviction selection mechanism 35 is provided to select evictable cached data for eviction from the cache. A cache compacting mechanism 40 is provided to evict evictable cached data from the cache and to store non-evictable cached data in fewer cache segments than were used to store the cached data prior to eviction of the evictable cached data.