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Graphics display system with unified memory architecture

  • US 9,077,997 B2
  • Filed: 01/22/2004
  • Issued: 07/07/2015
  • Est. Priority Date: 11/09/1998
  • Status: Expired due to Fees
First Claim
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1. A unified memory system comprising:

  • a memory that is shared by a plurality of devices including at least a central processing unit and a graphics processing unit;

    a memory request arbiter coupled to the memory, wherein the memory request arbiter performs real time scheduling of memory requests from different devices having different priorities, the unified memory system provides for real time scheduling of tasks, and provides access to memory by requesters that are sensitive to latency and do not have determinable periodic behavior;

    dual memory controllers, the dual memory controllers including a first memory controller and a second memory controller, the memory request arbiter including a first arbiter coupled to the first memory controller and a second arbiter coupled to the second memory controller, wherein the first arbiter and the second arbiter perform real time scheduling of memory requests, wherein memory requests to the memory shared by the plurality of devices are routed to a particular one of the first arbiter and the second arbiter based on the address of the memory request; and

    a memory select circuit receiving requests from the central processing unit and graphics processing unit, selecting one of the dual memory controllers and one of the first arbiter or second arbiter, and providing the request to the selected one of the dual memory controllers and the selected one of the first arbiter or second arbiter; and

    wherein a predetermined minimum interval between subsequent accesses by a device is enforced, and wherein said predetermined minimum interval is long enough for another device to access.

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