Vlsi Technology, Inc.

Koninklijke Philips Corporation N.V.

Rajeev Jayavant

William Desi Rhoden

Laura Elisabeth Simmons

Judson A Lehman

Morgan J Dempsey

Bradley W Cain

Huzefa H Cutlerywala

The present invention provides a low-cost computer system which includes a single sharable block of memory that can be independently accessible as graphics memory or main store system memory without performance degradation. Because the &ldquo;appetite&rdquo; for main system memory (unlike that of a display memory) is difficult to satisfy, the memory can be addressed by reallocating an unused portion of a display memory for system memory use. Reallocation of the unused display memory alleviates any need to oversize the display memory, yet realizes the cost effectiveness of using readily available memory sizes. Further, reallocation of the graphics memory avoids any need to separately consider both the system memory and the display memory in accommodating worst case operational requirements. In accordance with additional embodiments, improved efficiency of operation can be achieved to enhance concurrency between plural banks of memory when expansion memory is included. The addressable locations of the expansion memory can be mapped to the bottom of the available system address space, and addressable locations of any prior base system memory are moved above the expansion memory space.

Method and apparatus for providing and maximizing concurrent operations in a shared memory system which includes display memory

A Mini-PCI (MPCI) interface, and associated circuits and methods are provided for connecting a Peripheral Component Interconnect (PCI) device to one or more external devices. The MPCI interface, circuits and methods provide for a substantial if not full implementation of a PCI Local Bus without requiring the standard number of pins, traces, or signals. The MPCI interface includes a PCI/MPCI bridge connected between a PCI bus and to up to eight external devices in the form of MPCI devices and linear memory devices. The PCI/MPCI bridge is capable of receiving an incoming PCI transaction and multiplexing some of its signals together to create a corresponding incoming MPCI transaction. This incoming MPCI transaction may then be passed over an MPCI bus, having fewer lines and optimally operating at a higher frequency, the external devices. The process is reversed for outgoing transactions, i.e., the MPCI transactions are de-multiplexed to create PCI transactions. Additionally, the MPCI interface may also be configured to provide for direct access to linearly addressed memory devices without adding a PCI interface to the external interface. The invention may be implemented through integrated circuitry and/or computer implemented instructions, and may be included within a personal computer.

PCI bus with reduced number of signals

An improved bus architecture is provided in which the bus connects a single master to multiple targets including one primary target. Bus usage is predominately between the master and one primary target at a very high data transfer rate. Traffic between the master and other secondary targets has a much lower bandwidth requirement. The bus uses a single frequency clock for transfers involving the primary target and transfers involving the secondary targets. In accordance with one embodiment of the invention, the master is connected to the primary high bandwidth target using a high speed protocol and separate read and write data paths which are always driven (i.e., never tri-stated). Always driving the high speed data paths avoids the increased area and decreased performance that would be entailed by adding additional gating. The lower bandwidth targets are supported on a single bi-directional data path to minimize area. This lower bandwidth path has a different protocol and is only activated upon command from the master in order to reduce power dissipation. This construction is different from a bus bridge in that the master specifically initiates activity on the low bandwidth bus, based on the target's address. The master knows which path will process a cycle, and cycles are completed differently for each path.

Computing device having semi-dedicated high speed bus

In a text mode of a display controller, for each character of the text, a plurality of multiple-byte words are stored in a memory buffer. Each multiple-byte word contains an ASCII character code for the character, font attribute information for the character and at least one font line for the character. For each character font line to be displayed on the monitor, a multiple byte word is read. The attribute information and a first character font line are extracted from the multiple byte word. The display controller then constructs a character scan line for the character based on the attribute information and the first character font line. The character scan line may then be displaying on the monitor.

Method and apparatus for screen refresh bandwidth reduction for video

An integrated circuit with power conservation includes a number of functional blocks, each of which includes digital circuitry and at least one output control line, and a power controller coupled to the control lines. The output control lines develop clock control signals based upon a functional block's knowledge of the direction of data flow. The power controller the reduces power by deactivating functional blocks that are not needed as indicated by the clock control signals. More specifically, a system with power conservation includes a number of functional blocks capable of processing data, each of the functional blocks including a modulated clock input and N+1 clock control lines which reflect the direction of data flow, where N is a number of neighbors of a particular functional block, and a clock controller having an input clock, the clock controller being coupled to the modulated clock inputs and the clock control lines of the functional blocks. The clock controller is operative to modulate the input clock in accordance with the signals on the clock control lines to provide modulated clocks to each of the plurality of functional blocks. A method for reducing power consumption includes the steps of: a) receiving control signals from a number of functional blocks; b) selectively deactivating a particular functional block upon a request from that functional block or from another functional block; and c) activating the particular functional block upon a request from another functional block.

Method and apparatus for reducing power consumption in digital

An image is written to a data frame buffer for display by a monitor. The image includes a repeated pattern. The present invention uses a repeated pattern cache which is not large enough to simultaneously contain an entire repeated pattern. When writing a pixel of the image, a horizontal pattern offset and a vertical pattern offset for a destination location of the pixel are determined. If a scan line for the repeated pattern which corresponds to the vertical pattern offset does not reside in the repeated pattern cache, the scan line for the repeated pattern which corresponds to the vertical pattern offset is fetched into the repeated pattern cache. When the scan line for the repeated pattern which corresponds to the vertical pattern offset resides in the repeated pattern cache, the pixel is accessed at a location in the repeated pattern cache at a location which corresponds to the horizontal pattern offset. The accessed pixel is written to the buffer.

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Phoenix, AZ, United States of America

Rajeev Jayavant