摘要:
A computer system having a core logic chipset that functions as a bridge between an Accelerated Graphics Port ("AGP") bus device such as a graphics controller, and a host processor and computer system memory wherein a Graphics Address Remapping Table ("GART table") is used by the core logic chipset to remap virtual memory addresses used by the AGP graphics controller into physical memory addresses that reside in the computer system memory. The GART table enables the AGP graphics controller to work in contiguous virtual memory address space, but actually use non-contiguous blocks or pages of physical system memory to store textures, command lists and the like. The GART table is made up of a plurality of entries, each entry comprising an address pointer to a base address of a memory page, and feature flags that may be used to customize the associated memory page.
摘要:
A computer system having a core logic chipset that functions as a bridge between an Accelerated Graphics Port ("AGP") bus device such as an AGP graphics controller, and a host processor and computer system memory wherein AGP transaction read requests are merged from the AGP graphics controller and retired when these requests are within a cacheline of the memory being accessed. The core logic chipset will request a memory cacheline read as it begins processing a current AGP transaction read request. Once the memory read access is initiated, the transaction read request will be popped off an AGP request queue in order to evaluate the next in order transaction request. If the next request can be partially or completely retired by the memory read access previously started, then the memory access that would have been normally required may be skipped and the data from the previous memory read access is used instead. This AGP read transaction merging may continue until the next in order transaction read request is located in a different cacheline of memory or the original memory request is ready to return data. A memory data buffer may also be utilized to store unused quadwords of the cacheline read from a memory access so that some subsequent AGP transaction requests may be retired without having to access a previously read cacheline of memory.
摘要:
A computer system having an expansion base for docking a portable portion of the computer system includes a bridge circuit for adaptively decoding addresses on a bus based on the docking status. Both the expansion base and the portable portion include the bridge circuit for passing cycles from a peripheral component interconnect (PCI) bus to an industry standard architecture (ISA) bus. The bridge includes internal devices and configuration registers for controlling the decoding. Bus cycles intended for internal devices and external devices connected to each respective ISA bus of the bridge circuits are positively decoded. Cycles not positively decoded and claimed are subtractively decoded by one of the bridge circuits depending on the docking status.
摘要:
A computer system having an expansion base for docking a portable portion of the computer system includes a bridge circuit for adaptively decoding addresses on a bus based on the docking status. Both the expansion base and the portable portion include the bridge circuit for passing cycles from a peripheral component interconnect (PCI) bus to an industry standard architecture (ISA) bus. The bridge includes internal devices and configuration registers for controlling the decoding. Bus cycles intended for internal devices and external devices connected to each respective ISA bus of the bridge circuits are positively decoded. Cycles not positively decoded and claimed are subtractively decoded by one of the bridge circuits depending on the docking status.
摘要:
A portable computer can be “hot” docked to one or more expansion devices, such as a drive wedge and a port replicator. As such, the expansion devices can be connected to and disconnected from the portable computer while portable computer is powered on and fully operational. The portable computer includes control logic that detects when an expansion device is connected to or disconnected from the portable computer and asserts an SMI or equivalent interrupt signal to the computer's CPU to initiate a sequence of events by which the computer determines whether an expansion device has been connected or disconnected. If the CPU determines that the expansion device has been connected to the computer, the CPU appropriately reconfigures itself to communicate with the expansion device. If the expansion device is disconnected, the CPU also appropriately reconfigures itself to preclude communications with the disconnected device.
摘要:
A computer system having a core logic chipset that functions as a bridge between an Accelerated Graphics Port ("AGP") bus device such as a graphics controller, and a host processor and computer system memory wherein a Graphics Address Remapping Table ("GART table") is used by the core logic chipset to remap virtual memory addresses used by the AGP graphics controller into physical memory addresses that reside in the computer system memory. The GART table enables the AGP graphics controller to work in contiguous virtual memory address space, but actually use non-contiguous blocks or pages of physical system memory to store textures, command lists and the like. The GART table is made up of a plurality of entries, each entry comprising an address pointer to a base address of a page of graphics data in memory, and feature flags that may be used to customize the associated page. One of the feature flags is used as a Present Bit for a corresponding memory page. When the feature flag Present Bit is set, the memory page has been reserved in the physical memory for graphics data and an address translation may be carried out. When the feature flag Present Bit is clear, the memory page has not been reserved for graphics data in the physical memory and a determination must then be made whether to perform the translation or generate an error signal to the computer processor.
摘要:
A computer system having a core logic chipset that functions as a bridge between an Accelerated Graphics Port ("AGP") bus device such as a graphics controller, and a host processor and computer system memory wherein a Graphics Address Remapping Table ("GART table") is used by the core logic chipset to remap virtual memory addresses used by the AGP graphics controller into physical memory addresses that reside in the computer system memory. The GART table enables the AGP graphics controller to work in contiguous virtual memory address space, but actually use non-contiguous blocks or pages of physical system memory to store textures, command lists and the like. A plurality of AGP memory-mapped status and control registers are stored in the computer system memory, and are used for status and control of AGP functions in the computer system.
摘要:
A computer system having a core logic chipset that functions as a bridge between an Accelerated Graphics Port ("AGP") bus device such as a graphics controller, and a host processor and computer system memory wherein a Graphics Address Remapping Table ("GART table") is used by the core logic chipset to remap virtual memory addresses used by the AGP graphics controller into physical memory addresses that reside in the computer system memory. The GART table enables the AGP graphics controller to work in contiguous virtual memory address space, but actually use non-contiguous blocks or pages of physical system memory to store textures, command lists and the like. Contiguous virtual memory address space must be allocated for the AGP device within the addressable memory space of the computer system, typically 4 gigabytes using 32 bit addressing. The required amount of virtual memory address space for AGP is determined from the AGP device and the information is put into a register of the core logic so that the computer system software may allocate the required amount of memory and assign a base address thereto during computer system startup or POST. An AGP Valid bit is set to indicate whether an AGP device is present or not. If the AGP device is not present, then no virtual memory address space is allocated during the computer system startup.
摘要:
Hardware logic within a host bridge that connects a system bus to a peripheral bus using PCI bus architecture or a peripheral bus that uses a bus architecture similar to PCI. The hardware optimizes the speed at which data transfers are accomplished between the buses while translating the data transfers between the different architectures of the two buses.
摘要:
Hardware logic within a host bridge that connects a CPU local bus to a peripheral bus that determines if data to be transmitted on the CPU local bus is non-contiguous and, if so, substitutes contiguous data for the non-contiguous data to ensure that the CPU local bus does not malfunction. Simultaneously, the hardware translates data transfers between a peripheral bus that is limited by its architecture to data strings of a standard length and a CPU local bus that permits dynamic bus sizing.