Abstract: A microprocessor apparatus is provided including multiple functional units, some of which can enter a power reduction mode to decrease overall power consumption when needed. The functional units generate respective activity signals to indicate the level of activity of each of the functional units. The activity outputs are monitored by utilization assessment logic to determine a current total power consumption value for the microprocessor. The microprocessor is capable of successively entering a series of power reduction modes when the current total power consumption value is greater than a threshold power value of a specified power profile.

Abstract: An apparatus and method for sharing cache lines within a split data/code cache is provided. The invention utilizes cache snoop and state control, coupled to both a data cache and a code cache, which allows the data cache to snoop fetches to the code cache, and allows the code cache to snoop reads and writes to the data cache. In addition, cache snoop and state control modifies the state of a particular cache line within both of the caches according to the MESI cache coherency protocol to allow a single cache line to reside in both the data cache, and the code cache, in a Shared state. The invention allows the shared cache line to be fetched from the code cache, and retrieved from the data cache, until it is overwritten or modified in the data cache. In one embodiment, an instance of a cache line within either the code or data cache can be snarfed into the other cache, and marked as shared.

Abstract: A method and apparatus for tracking the fill status of sub cache line locations during a cache line fill operation is provided. The tracking system monitors the data cycles of a burst read during a cache line fill, and sets indicators pertaining to which of the sub cache lines within the cache line have been filled. Cache control utilizes the indicators to make those sub cache lines that have been filled available to a processing system as they are filled, rather than waiting for the entire cache line to be filled. Data is stored directly into sub cache line locations without requiring a cache line buffer.

Abstract: An apparatus and method for organizing a data array within a cache system to store a plurality of physical pages of data. A single data array is associated with a plurality of tag arrays, each tag array tracking a page size portion of the data array. Indexing into each of the tag arrays is accomplished using the page index from either of the virtual address or the physical address. In addition, selection of indexed tags from the tag arrays is performed by array selection logic which utilizes portions of either of the virtual page number or the physical page number.

Abstract: An apparatus and method which provides specified hold times for communication signals transmitted from a processing device that is capable of operating at different frequencies, to external devices, is provided. The apparatus includes a clock multiplier which generates an internal clock signal which is a multiple of an external clock, a ring oscillator, which provides a number of outputs of the same frequency as the internal clock, but at fixed phase offsets from the internal clock, and clock select circuitry, which selects one of the outputs from the ring oscillator, depending on the speed of the internal clock, to be used as a drive clock signal for a bus unit. Selection of one of the phase offset outputs provides for a specified hold time regardless of the internal clock speed of the processing device.

Abstract: A method and apparatus for tracking the fill status of subcache line locations during a cache line fill operation is provided. The tracking system monitors the data cycles of a burst read during a cache line fill, and sets indicators pertaining to which of the sub cache lines within the cache line have been filled. Cache control utilizes the indicators to make those sub cache lines that have been filled available to a processing system as they are filled, rather than waiting for the entire cache line to be filled. Data is stored directly into sub cache line locations without requiring a cache line buffer.