Abstract: A memory circuit for use in a data processing circuit is described, in which memory cells have at least two states, each state being determined by both a first voltage level corresponding to a first supply line and a second voltage level corresponding to a second supply line. The memory circuit comprises a readable state in which information stored in a memory cell is readable and an unreadable state in which information stored in said memory cell is reliably retained but unreadable. Changing the first voltage level but keeping the second voltage level substantially constant effects a transition between the readable state and the unreadable state. In use, the static power consumption of the memory cell in the unreadable state is less than static power consumption of the memory cell in the readable state.

Abstract: There is provided an apparatus for processing data under control of a program having program instructions and subgraph suggestion information identifying respective sequences of program instructions corresponding to computational subgraphs identified within said program, said apparatus comprising: a memory operable to store a program formed of separate program instructions; processing logic operable to execute respective separate program instructions from said program; and accelerator logic operable in response to reaching an execution point within said program associated with a subgraph suggestion to execute a sequence of program instructions corresponding to said subgraph suggestion as an accelerated operation instead of executing said sequence of program instructions as respective separate program instructions with said processing logic.

Abstract: There is provided an information processor for executing a program comprising a plurality of separate program instructions: processing logic operable to individually execute said separate program instructions of said program; an operand store operable to store operand values; and an accelerator having an array comprising a plurality of functional units, said accelerator being operable to execute a combined operation corresponding to a computational subgraph of said separate program instructions by configuring individual ones of said plurality of functional units to perform particular processing operations associated with one or more processing stages of said combined operation; wherein said accelerator executes said combined operation in dependence upon operand mapping data providing a mapping between operands of said combined operation and storage locations within said operand store and in dependence upon separately specified configuration data providing a mapping between said plurality of functional units a

Abstract: An accelerator 120 is tightly coupled to the normal execution unit 110. The operand store, which could be a register file 130, a stack based operand store or other operand store is shared by the execution unit and the accelerator unit. Operands may also be accessed as immediate values within the instructions themselves. The sequences of individual program instructions corresponding to computational subgraphs remain within a program but can be recognized by the accelerator as suitable for acceleration and when encountered are executed by the accelerator instead of by the normal execution unit. Within such tightly coupled arrangement problems can arise due to a lack of register resources within the system. The present technique provides that at least some intermediate operand values which are generated within the accelerator, but are determined not to be referenced outside of the computational subgraph concerned, are not written to the operand store.

Abstract: Voltage-binning of individual integrated circuits is achieved by operating those integrated circuits at a plurality of required clock frequencies and for each of those frequencies determining the minimum supply voltage level which produces a pass result for a series of applied test vectors.

Abstract: There is provided a memory for storing data comprising: a fast data reading mechanism operable to read a data value from said memory to generate a fast read result that is output from said memory for further processing; a slow data reading mechanism operable to read said data value from said memory to generate a slow read result available after said fast read result has been output for further processing, said slow data reading mechanism being less prone to error in reading said data value than said fast data reading mechanism; a comparator operable to compare said fast read result and said slow read result to detect if said fast read result differs from said slow read result; and error repair logic operable if said comparator detects that said fast read result differs from said slow read result to suppress said further processing using said fast read result, to output said slow read result in place of said fast read result and to restart said further processing based upon said slow read result.

Abstract: There is provided a memory for storing data comprising: a fast data reading mechanism operable to read a data value from said memory to generate a fast read result that is output from said memory for further processing; a slow data reading mechanism operable to read said data value from said memory to generate a slow read result available after said fast read result has been output for further processing, said slow data reading mechanism being less prone to error in reading said data value than said fast data reading mechanism a comparator operable to compare said fast read result and said slow read result to detect if said fast read result differs from said slow read result; and error repair logic operable if said comparator detects that said, fast read result differs from said slow read result to suppress said further processing using said fast read result, to output said slow read result in place of said fast read result and to restart said further processing based upon said slow read result.

Abstract: Voltage-binning of individual integrated circuits is achieved by operating those integrated circuits at a plurality of required clock frequencies and for each of those frequencies determining the minimum supply voltage level which produces a pass result for a series of applied test vectors.

Abstract: A performance counter accumulates a value by periodically adding a variable increment value representing the amount of work performed. The increment value can be varied in dependence upon the processor clock frequency and may be adjusted under hardware and/or software control.

Abstract: A multi-processing system 2 measures the degree of parallelism achieved in executing program instructions and uses this to dynamically control the clock speeds and supply voltage levels applied to different processor cores 4, 6 so as to reduce the overall amount of energy consumed by matching the processing performance achieved to the clock speeds and voltage levels used.

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: There is provided an integrated circuit comprising:

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: There is provided a memory for storing data comprising:

Abstract: A memory circuit for use in a data processing circuit is described, in which memory cells have at least two states, each state being determined by both a first voltage level corresponding to a first supply line and a second voltage level corresponding to a second supply line. The memory circuit comprises a readable state in which information stored in a memory cell is readable and an unreadable state in which information stored in said memory cell is reliably retained but unreadable. Changing the first voltage level but keeping the second voltage level substantially constant effects a transition between the readable state and the unreadable state. In use, the static power consumption of the memory cell in the unreadable state is less than static power consumption of the memory cell in the readable state.

Abstract: An integrated circuit includes a plurality of processing stages each including processing logic 2, a non-delayed latch 4, a delayed latch 8 and a comparator 6. The non-delayed latch 4 captures an output from the processing logic 2 at a non-delayed capture time. At a later delayed capture time, the delayed latch 8 also captures a value from the processing logic 2. The comparator 6 compares these values and if they are not equal this indicates that the non-delayed value was captured too soon and should be replaced by the delayed value. The non-delayed value is passed to the subsequent processing stage immediately following its capture and accordingly error recovery mechanisms are used to suppress the erroneous processing which has occurred by the subsequent processing stages, such as gating the clock and allowing the correct signal values to propagate through the subsequent processing logic before restarting the clock.

Abstract: Performance level selection is carried out by calculating a plurality of performance requests using a plurality of performance request calculating algorithms, combining those different performance requests to form a global performance request and then selecting a performance level in dependence upon the global performance level request. The performance request calculating algorithms can be arranged in a hierarchy with their performance requests evaluated in a sequence starting from the least dominant position in the hierarchy and moving through to the most dominant position in the hierarchy. Commands may accompany each performance level request to specify how it should be combined with other performance level requests.

Abstract: A target processor performance level is calculated from a utilisation history of a processor in performance of a plurality of processing tasks. The method comprises calculating a task work value indicating processor utilisation in performing a given processing task within a predetermined task time-interval and calculating a target processor performance level in dependence upon the task work value.

Abstract: There is provided a system having: