Computer graphics processing and selective visual display system – Computer graphics display memory system – Memory allocation
Reexamination Certificate
2001-09-24
2002-10-08
Tung, Kee M. (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics display memory system
Memory allocation
C345S532000, C345S520000
Reexamination Certificate
active
06462745
ABSTRACT:
BACKGROUND OF THE INVENTION
This patent application is a continuation of U.S. patent application Ser. No. 09/206,677, filed Dec. 7, 1998, now U.S. Pat. No. 6,326,973, and entitled “Method And System For Allocating AGP/GART Memory From the Local AGP Memory Controller In A Highly Parallel System Architecture (HPSA).”
1. Field of the Invention
The present invention relates to computer systems using at least one accelerated graphics port (AGP) with at least two core logic chip sets, and more particularly, in allocating AGP/GART memory from the system memory local to the AGP device.
2. Description of the Related Technology
Use of computers, especially personal computers, in business and at home is becoming more and more pervasive because the computer has become an integral tool of most information workers who work in the fields of accounting, law, engineering, insurance, services, sales and the like. Rapid technological improvements in the field of computers have opened up many new applications heretofore unavailable or too expensive for the use of older technology mainframe computers. These personal computers may be stand-alone workstations (high-end individual personal computers), desktop personal computers, portable laptop computers and the like. Moreover, personal computers may be linked together in a network by a “network server” which is also a personal computer which may have a few additional features specific to its purpose in the network. The network server may be used to store massive amounts of data, and may facilitate interaction of the individual workstations connected to the network for electronic mail (“E-mail”), document databases, video teleconferencing, white boarding, integrated enterprise calendar, virtual engineering design and the like. Multiple network servers may also be interconnected by local area networks (“LAN”) and wide area networks (“WAN”).
A significant part of the ever-increasing popularity of the personal computer, besides its low cost relative to just a few years ago, is its ability to run sophisticated programs and perform many useful and new tasks. Personal computers today may be easily upgraded with new peripheral devices for added flexibility and enhanced performance. A major advance in the performance of personal computers (both workstation and network servers) has been the implementation of sophisticated peripheral devices such as video graphics adapters, local area network interfaces, SCSI bus adapters, full motion video, redundant error checking and correcting disk arrays, and the like. These sophisticated peripheral devices are capable of data transfer rates approaching the native speed of the computer system's microprocessor central processing unit (“CPU”). The peripheral devices' data transfer speeds are achieved by connecting the peripheral devices to the microprocessor(s) and associated system random access memory through high-speed expansion local buses. Most notably, a high speed expansion local bus standard has emerged that is microprocessor independent and has been embraced by a significant number of peripheral hardware manufacturers and software programmers. This high-speed expansion bus standard is called the “Peripheral Component Interconnect” or “PCI.” A more complete definition of the PCI local bus may be found in the following specifications: PCI Local Bus Specification, revision 2.1; PCI/PCI Bridge Specification, revision 1.0; PCI System Design Guide, revision 1.0; PCI BIOS Specification, revision 2.1, and Engineering Change Notice (“ECN”) entitled “Addition of ‘New Capabilities’ Structure,” dated May 20, 1996, the disclosures of which are hereby incorporated by reference. These PCI specifications and ECN's are available from the PCI Special Interest Group, P.O. Box 14070, Portland, Oreg. 97214.
A computer system has a plurality of information (data and address) busses. These busses include a host bus, a memory bus, at least one high-speed expansion local bus such as the PCI bus, and other peripheral buses such as the Small Computer System Interface (SCSI), Extension to Industry Standard Architecture (EISA), and Industry Standard Architecture (ISA). The microprocessor(s) of the computer system communicates with main memory and with the peripherals that make up the computer system over these various buses. The microprocessor(s) communicates to the main memory over a host bus to a memory bus bridge. The peripherals, depending on their data transfer speed requirements, are connected to the various buses which are connected to the microprocessor host bus through bus bridges that detect required actions, arbitrate, and translate both data and addresses between the various buses.
Increasingly sophisticated microprocessors have revolutionized the role of the personal computer by enabling complex applications software to run at mainframe computer speeds. The latest microprocessors have brought the level of technical sophistication to personal computers that, just a few years ago, was available only in mainframe and mini-computer systems. Some representative examples of these new microprocessors are the “PENTIUM” and “PENTIUM PRO” (registered trademarks of Intel Corporation). Advanced Micro Devices, Cyrix, IBM, Digital Equipment Corp., and Motorola also manufacture advanced microprocessors.
These sophisticated microprocessors have, in turn, made possible running complex application programs using advanced three dimensional (“3-D”) graphics for computer aided drafting and manufacturing, engineering simulations, games and the like. Increasingly complex 3-D graphics require higher speed access to ever-larger amounts of graphics data stored in memory. This memory may be part of the video graphics processor system, but, preferably, would be best (lowest cost) if part of the main computer system memory. Intel Corporation has proposed a low cost but improved 3-D graphics standard called the “Accelerated Graphics Port” (AGP) initiative. With AGP 3-D, graphics data, in particular textures, may be shifted out of the graphics controller local memory to computer system memory. The computer system memory is lower in cost than the graphics controller local memory and is more easily adapted for a multitude of other uses besides storing graphics data.
The Intel AGP 3-D graphics standard defines a high-speed data pipeline, or “AGP bus,” between the graphics controller and system memory. This AGP bus has sufficient bandwidth for the graphics controller to retrieve textures from system memory without materially affecting computer system performance for other non-graphics operations. The Intel 3-D graphics standard is a specification, which provides signal, protocol, electrical, and mechanical specifications for the AGP bus and devices attached thereto. The original specification is entitled “Accelerated Graphics Port Interface Specification Revision 1.0,” dated Jul. 31, 1996, the disclosure of which is hereby incorporated by reference. The newest specification is entitled “Preliminary Draft of Accelerated Graphics Port Interface Specification, Preliminary Draft of Revision 2.0,” dated Dec. 10, 1997. These AGP Specifications are available from Intel Corporation, Santa Clara, Calif.
The AGP interface specification uses the 66 MHz PCI (Revision 2.1) specification as an operational baseline, with three performance enhancements to the PCI specification which are used to optimize the AGP Specification for high performance 3-D graphics applications. These enhancements are: 1) pipelined memory read and write operations, 2) demultiplexing of address and data on the AGP bus by use of side-band signals, and 3) data transfer rates of 133 MHz for data throughput in excess of 500 megabytes per second (“MB/s”). The remaining AGP Specification does not modify the PCI specification, but rather provides a range of graphics-oriented performance enhancements for use by 3-D graphics hardware and software designers. The AGP Specification is neither meant to replace or diminish full use of the PCI standard in the computer system. The AGP Specification create
Behrbaum Todd S.
Horan Ronald T.
Johnson, Jr. Stephen R.
Theisen John E.
Compaq Information Technologies Group L.P.
Conley & Rose & Tayon P.C.
Tung Kee M.
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