Abstract: A method and circuitry are provided for latching information. The information is selectively transferred from a selected one of: a first node (DIN) to a second node (416); and a third node (SIN) to a fourth node (419a-b). The transferred information is selectively latched by coupling the second node (416) to the fourth node (419a-b) in response to a signal (308, 410).

Abstract: A processing system and method of operation are provided. First translation information is stored. A logic state of a first match line is selectively modified in response to a comparison between the first translation information and a first portion of a first address. Second translation information is stored. A logic state of a second match line is selectively modified in response to a comparison between the second translation information and a second portion of the first address. The logic state of the second match line is selectively modified in response to the logic state of the first match line. A second address is selectively output in response to the logic state of the second match line.

Abstract: A processing system and method of operation are provided. At least one execution unit processes information of a register in response to an instruction specifying the register. Each of multiple control units selectively allocates a respective one of multiple buffers to store the information in response to the instruction.

Abstract: A fault tolerant processing system including a prediction RAM employs a Lock Step Compare routine. The method developed allows the processing system to recover from single event upsets. In initialization, the branch prediction RAM is set to a known value. An engineering balance is achieved by adding logic to detect a branch RAM error and incurring the delay of re-initializing the entire RAM only when a RAM error has been detected.

Abstract: A system and method for denormalizing a floating point result is disclosed. Denormalized operands are capable of representing much smaller values than can be represented by a number normalized under the ANSI/IEEE standard 754-1985 that governs the representation of numbers in floating point notation to ensure uniformity among floating point notation users. The majority of results will be normalized operands and therefore the floating point unit pipeline is optimized to produce normalized results but contains wider exponent fields in order to represent values received as denormalized numbers. In order to return the result as a denormalized number with the smaller ANSI/IEEE exponent field, denormalization is accomplished by using the same pipeline resources by means of the floating point unit feedback path and uses one of the exponent equalizing alignment shifters and an incrementor in order to round the denormalized result.

Abstract: A processing system and method of operation are provided. In response to multiple branch instructions, an instruction is processed prior to execution of the branch instructions. In response to execution of any of the branch instructions, the processing of the instruction is cancelled prior to completion of the executed branch instruction.

Abstract: An interleaved data cache array which is divided into two subarrays is provided for utilization within a data processing system. Each subarray includes a plurality of cache lines wherein each cache line includes a selected block of data, a parity field, a content addressable field containing a portion of an effective address for the selected block of data, a second content addressable field contains a portion of the real address for the selected block of data and a data status field. A separate effective address port and real address port permit parallel access to the cache without conflict in separate subarrays and a subarray arbitration logic circuit is provided for attempted simultaneous access of a single subarray by both the effective address port and the real address port.

Abstract: A method and system within a processor are disclosed for executing selected instructions among a number of instructions stored within a memory, wherein the processor has a maximum of instructions that can dispatched for execution during each processor cycle. A subset of the instructions are fetched from the memory for execution. A determination is then made whether the set of instructions includes an unresolved branch instruction. In response to a determination that the set of instructions includes an unresolved branch instruction, a prediction is made whether a branch indicated by the branch instruction will be taken or will not be taken. In response to a prediction that the branch will be taken, a nonsequential target instruction indicated by the branch instruction is fetched from memory.

Abstract: A method and system are disclosed for processing instructions within a data processing system including a processor having a plurality of execution units. According to the method of the present invention, a number of instructions stored within a memory within the data processing system are retrieved from memory. A selected instruction among the number of instructions is decoded to determine if the selected instruction would be noneffective if executed by the processor. In a preferred embodiment of the present invention, noneffective instructions include instructions with invalid opcodes and instructions that would not change the value of any data register within the processor. In response to determining that the selected instruction would be noneffective if executed by the processor, the selected instruction is recoded into a specified instruction format prior to dispatching the selected instruction to one of the number of execution units.

Abstract: A method and system are provided for transferring information between multiple buses. Information is transferred through a first bus between multiple first bus devices. Information is transferred through a second bus between multiple second bus devices. Information is transferred through logic between the first and second buses. Using the logic, an action of a first bus device is enabled in response to a condition in which a second bus device waits for the action while the first bus device waits for a separate action on the second bus.

Abstract: A method for selectively executing speculative load instructions in a high-performance processor is disclosed. In accordance with the present disclosure, when a speculative load instruction for which the data is not stored in a data cache is encountered, a bit within an enable speculative load table which is associated with that particular speculative load instruction is read in order to determine a state of the bit. If the associated bit is in a first state, data for the speculative load instruction is requested from a system bus and further execution of the speculative load instruction is then suspended to wait for control signals from a branch processing unit. If the associated bit is in a second state, the execution of the speculative load instruction is immediately suspended to wait for control signals from the branch processing unit.

Abstract: A method and system in a data processing system for transferring data from a first device to a second device within the data processing system. The data processing system includes a data bus, an address bus, a first address space associated with a memory and a second address space associated with an input/output device. Initially, a transfer signal is transmitted in the data processing system. The transfer signal identifies the transfer as a transfer concerning an address in the second address space associated with the input/output device. A first address package is then transmitted to the second device from the first device on the address bus. The first address package includes a transfer identifier, a first identifier associated with the first device and a second identifier associated with the second device. A second address package, comprising a byte count and an address, are transmitted to the second device from the first device on the address bus.

Abstract: An apparatus for handling special cases outside of normal floating-point arithmetic functions is provided that is used in a floating-point unit used for calculating arithmetic functions. The floating-point unit generates an exponent portion and a mantissa portion and a writeback stage is coupled to the exponent portion and to the mantissa portion and is specifically used to handle the special cases outside the normal float arithmetic functions. A spill stage is also provided and is coupled to the writeback stage to receive a resultant exponent and mantissa. A register file unit is coupled to the writeback stage and the spill stage through a plurality of rename busses, which are used to carry results between the writeback stage and spill stage and the register file. The spill stage is serially coupled to the writeback stage so as to provide a smooth operation in the transition of operating on the results from the writeback stage for the exponent and mantissa.

Abstract: A fault-tolerant computer system having shadow registers for storing the contents of a primary array into a shadow array at the completion of a stored instruction execution. This is accomplished in one clock cycle with all registers being shadowed simultaneously. During rollback of execution steps for a checkpoint retry, the shadow register files provide a signal cycle unload of the shadow array into the primary array. LSSD latches are used in the shadow register file.

Abstract: A method and structure are provided for connecting to integrated circuitry. A connectivity cell includes multiple terminals formed within the integrated circuitry. The connectivity cell further includes at least one metal layer connected to at least one of the terminals. A first area is a substantially minimal area including the connectivity cell. A second area is a substantially minimal area including at least a part of each of multiple portions of the integrated circuitry. The portions are connectable to respective ones of the terminals while having a placement flexibility relative to the terminals. This placement flexibility of the portions is substantially equal to a placement flexibility of the second area within the first area.

Abstract: A processing system and method of operation are provided. Multiple instructions are dispatched in a sequence to execution circuitry. Ones of the instructions are executed with the execution circuitry, and respective results are output in response thereto, Each executed instruction is completed in response to finishing execution of each instruction preceding the executed instruction in the sequence, independent of whether the results are stored in at least one storage location specified by the completed instructions.

Abstract: A method and apparatus are provided for generating a phase-controlled clock signal within a microprocessor. A first clock signal having a first frequency is input. After a reset event, the first clock signal transitions in a first direction at a time t. A second clock signal is output having a second frequency related to the first frequency by a non-integer ratio. The second clock signal transitions in the same direction as the first clock signal at time t.

Abstract: A data processor (12) has a branch prediction unit (28) that predicts conditional branch instructions and a control unit (70) therein that monitors the number of unresolved branch instructions. This control unit selectively allows the data processor to fetch the instructions indicated by the branch prediction unit from an external memory system depending upon the number of unresolved branch instructions. The particular threshold number of unresolved branch instructions is user programmable. The data processor thereby limits its bus accesses to those occasions when it is reasonably sure that it will need the indicated instructions.

Abstract: A method and system are provided for self-timed processing. An operation is executed with a functional unit. A timing of the operation execution is simulated with a tracking element, and a tracking signal is output. A sequencing signal is varied to the functional unit in response to the tracking signal.

Abstract: A memory cache (14) has a semi-associative cache array (50), a cache reload buffer (40), and a cache reload buffer driver (42). The memory cache writes received data to the cache reload buffer and waits until the data is requested again before it invalidates any cache aliased entries in the semi-associative cache array. This invalidation step requires no dedicated cycle but instead is a result of the memory cache being able to simultaneously read from the semi-associative cache array and the cache reload buffer.