摘要:
A method for synchronous broadcasting of multiple bytes over a VME bus broadcasts multiple bytes of data across the VME bus using hardware which interfaces between the bus and attached devices. An VME address modifier code is used to identify the type of broadcast and is sent by a master device, without requiring any response from the slave devices. In a first type of broadcast an address location is transmitted over the address bus and a data message is transmitted over the data bus. In a second type of broadcast data messages are transmitted over both the data and the address buses. Multiple broadcast cycles are used to transmit the desired amount of data. An address strobe qualifies the address and data buses for a message broadcast cycle and is used by the receiving slave to clock in the message.
摘要:
A method and apparatus for executing instructions in a pipeline processor. The method decreases the latency between an instruction cache and a pipeline processor when bubbles occur in the processing stream due to an execution of a branch correction, or when an interrupt changes the sequence of an instruction stream. The latency is reduced when a decode stage for detecting branch prediction and a related instruction queue location have invalid data representing a bubble in the processing stream. Instructions for execution are inserted in parallel into the decode stage and instruction queue, thereby reducing by one cycle time the length of the pipeline stage.
摘要:
A system and structure for snooping cache memories of several snooping masters connected to a bus macro, wherein each non-originating snooping master has a cache memory, and wherein some, but less than all the cache memories, may have the data requested by an originating snooping master and wherein the needed data in an non-originating snooping master is marked as updated, and wherein a main memory having addresses for all data is connected to the bus macro. Only those non-originating snooping masters which may have the requested data are queried. All the non-originating snooping masters that have been queried reply. If a non-originating snooping master has the requested data marked as updated, that non-originating snooping master returns the updated data to the originating snooping master and possibly to the main memory. If none of the non-originating snooping masters has the requested data marked as updated, then the requested data is read from main memory.
摘要:
A system and method for transferring data between a single channel unit and multiple asynchronous storage devices. One embodiment of the present invention uses read strobe signals to indicate when the storage devices are to send data over a data bus, and to initiate a validity count-down which indicates when the data on the data bus is valid. When the count-down has completed, the data on the data bus is sampled. Another embodiment further includes checking the data for array parity errors while the data is sent and received to and from the storage devices.
摘要:
A method and system for avoiding various hazards for instructions which are propagating through a microprocessor pipeline. When a plurality of instructions exist within the pipeline which read and write the same value, a vector is established to distinguish the older from the newer instructions. Further, before instructions are dispatched for execution, pointers are generated which identify the particular instruction which had the operand or parameter value needed. Accordingly, by monitoring both the recent vector and pointers, dated dependency hazards can be avoided.
摘要:
A method and apparatus are provided for determining power events on an I/C chip for undissipated power to the chip, and wherein the chip includes a plurality of separately regulatable power consumers. A structure is provided for monitoring the occurrence of each power event to each power consumer, and determining the dissipation of power from each power event, and controlling power used by the chip responsive to the amount of undissipated power.
摘要:
A method and system for a pipelined bus interface macro for use in interconnecting devices within a computer system. The system and method utilizes a pipeline depth signal that indicates a number N of discrete transfer requests that may be sent by a sending device and received by a receiving device prior to acknowledgment of a transfer request by the receiving device. The pipeline depth signal may be dynamically modified, enabling a receiving device to decrement or increment the pipeline depth while one or more unacknowledged requests have been made. The dynamic modifications may occur responsive to many factors, such as an instantaneous reduction in system power consumption, a bus interface performance indicator, a receiving device performance indicator or a system performance indicator.
摘要:
A system and method for accessing a data cache having at least two ways for storing data at the same addresses. A first and second tag memory store first and second sets of tags identifying data stored in each of the ways. A translation device determines from a system address a tag identifying one of the ways. A first comparator compares tags in the address with a tag stored in the first tag memory. A second comparator compares a tag in the address with a tag stored in the second tag memory. A clock signal supplies clock signals to one or both of the ways in response to an access mode signal. The system can be operated so that either both ways of the associative data cache are clocked, in a high speed access mode, or it can apply clock signals to only one of the ways selected by an output from the first and second comparators in a power efficient mode of operation.
摘要:
An LRU array and method for tracking the accessing of lines of an associative cache. The most recently accessed lines of the cache are identified in the table, and cache lines can be blocked from being replaced. The LRU array contains a data array having a row of data representing each line of the associative cache, having a common address portion. A first set of data for the cache line identifies the relative age of the cache line for each way with respect to every other way. A second set of data identifies whether a line of one of the ways is not to be replaced. For cache line replacement, the cache controller will select the least recently accessed line using contents of the LRU array, considering the value of the first set of data, as well as the value of the second set of data indicating whether or not a way is locked. Updates to the LRU occur after each pre-fetch or fetch of a line or when it replaces another line in the cache memory.
摘要:
A method and apparatus for executing instructions in a pipeline processor. The method decreases the latency between an instruction cache and a pipeline processor when bubbles occur in the processing stream due to an execution of a branch correction, or when an interrupt changes the sequence of an instruction stream. The latency is reduced when a decode stage for detecting branch prediction and a related instruction queue location have invalid data representing a bubble in the processing stream. Instructions for execution are inserted in parallel into the decode stage and instruction queue, thereby reducing by one cycle time the length of the pipeline stage.