Abstract: A processor having multiple independent engines can concurrently support a number of independent processes or operation contexts. The processor can independently schedule instructions for execution by the engines. The processor can independently switch the operation context that an engine supports. The processor can maintain the integrity of the operations performed and data processed by each engine during a context switch by controlling the manner in which the engine transitions from one operation context to the next. The processor can wait for the engine to complete processing of pipelined instructions of a first context before switching to another context, or the processor can halt the operation of the engine in the midst of one or more instructions to allow the engine to execute instructions corresponding to another context. The processor can affirmatively verify completion of tasks for a specific operation context.

Abstract: Software can freeze portions of a pipeline operation in a processor by asserting a predetermined freeze register in the processor. The processor halts operations relating to portions of a common pipeline processing in response to an asserted freeze register. Processor resources that operate downstream from the common pipeline continue to process any scheduled instructions. The processor is prevented from initiating any context switching in which a processor resource is allocated to a different channel. The processor stops supplying any additional data to downstream resources and ensures that the interface to downstream resources is clear of previously sent data. The processor prevents state machines from making additional requests. The processor asserts an acknowledgement indication in response to the freeze assertion when the processing has reached a stable state. Software is allowed to manipulate states and registers within the processor. Clearing the freeze register allows processing to resume.

Abstract: The present invention introduces circuitry and systems for performing two-dimensional motion compensation using a three-dimensional pipeline, as well as methods of operating the same. According to an exemplary embodiment, image processing circuitry is provided and includes both a two-dimensional image pipeline, which is operable to process two dimensional image data to generate successive two-dimensional image frames, and a three-dimensional image pipeline, which is operable to process three-dimensional image data to render successive three-dimensional image frames. The image processing circuitry further includes dual mode sub-processing circuitry, which is associated with each of the two- and three-dimensional image pipelines. The dual mode sub-processing circuitry is operable to perform motion compensation operations associated with the two-dimensional image pipeline in one mode and to perform rasterization operations associated the three-dimensional image pipeline in another mode.

Abstract: There is disclosed an apparatus for providing a virtual PCI device for use in a processing system comprising a data processor having an external peripheral bus coupled thereto in which peripheral devices associated with the external peripheral bus are controlled by accessing configuration circuitry associated with each of the peripheral devices. The apparatus comprises: a) an address trap circuit for detecting a configuration cycle accessing a virtual configuration address space associated with the virtual PCI device and generating an enable signal in response and b) an interrupt generation circuit associated with the address trap circuit that receives the enable signal and, in response, generates an interrupt signal that causes the data processor to execute instructions stored in system memory associated with the virtual device.

Abstract: There is disclosed an apparatus for loading instructions into the instruction execution pipeline of a pipelined processor. The apparatus for loading instructions comprises: 1) an instruction loading circuit that loads instructions from a first instruction thread into the instruction execution pipeline; and 2) a branch instruction detection circuit that detects a branch instruction in the first instruction thread. In response to the branch instruction detection, the instruction loading circuit stops loading instructions from the first instruction thread into the instruction execution pipeline and begins loading instructions from a second instruction thread into the instruction execution pipeline.

Abstract: An adapter for use in a multi-media workstation includes a device which accepts real-time video information at a first size, reduces the size to a selected one of a plurality of available sizes and places the reduced real-time video information into a selected area of the video memory of a computer graphic display device. Thereafter, the scaled real-time video information is displayed with other computer graphics applications, in a sub-window of the screen of the display device.

Abstract: A content addressable memory in accordance with the present invention includes a number of bistable memory cells having as inputs thereto first and second bit lines and an address line, and a COMPARE circuit connected to each of the memory cells so as to provide the COMPARE function without loading the first and second bit lines and including means for inhibiting current flow when a miscompare occurs.

Abstract: The use of a high speed cache memory may be selectively controlled when a data processing task is interrupted in response to an interrupt signal, in order to prevent the interrupt from chilling the cache when insufficient performance enhancement will be realized. Disturbing the cache memory during performance of an interrupting task is prevented, thereby increasing the hit ratio of the cache when the interrupted task is resumed. Cache control information may be incorporated into a program status vector or program status word which is loaded into a program status register on occurrence of an interrupt.

Abstract: A reconfigurable set associative cache memory can be reconfigured from 2.sup.x way to 2.sup.y way set associative cache memory by effectively merging a predetermined number of least significant bits of the tag field of the main memory address with the line field of the main memory address. The effective merging is provided by logically merging least significant bits of the tag field with a reconfiguration designation. As a result, Y-X+1 different configurations of cache memory can be obtained using the Y-X least significant bits of the tag field merged with the cache memory address.

Abstract: A processor adapted for parallel and/or pipelined interconnection with other like processors. An arithmetic logic unit has associated with it an output FIFO register stack having output data lines capable of parallel connection with the output data lines of other such processors, such output stack being loadable with a predetermined neutral value such that when the neutral value is present at their output data lines it permits the data present at the output lines of another such processor connected in parallel therewith to control the output data bus. The invention eliminates the need to have control over several such processors connected in parallel and/or pipelined configuration by way of external arbitration logic.