Abstract: A high speed connection apparatus, method, and system is provided for peripheral components on digital computer systems. The peripheral component interconnect (PCI) specification is used as a baseline for an extended set of commands and attributes. The extended command and the attribute are issued on the bus during the clock cycle immediately after the clock cycle when the initial command was issued. The extended commands and attributes utilize the standard pin connections of conventional PCI devices and buses making the present invention backward-compatible with existing (conventional) PCI devices and legacy computer systems. Alternate embodiments of the present invention utilize a side-band address port (SBA port) to enable multiple targets to receive the same set of data. The conventional PCI command encoding is modified and the extended command is used to qualify the type of transaction and the attributes being used by the initiator of the transaction.

Abstract: The present invention relates to a system and method for shadowing data of a first register and a second register of a computer system that share a common address. When a bus agent runs a write operation to the register address, retry logic of a first bridge circuit retries the write operation and masks access by the bus agent to the bus. Retry bus master logic reruns the write operation, in response to which the second bridge circuit subtractively decodes the rerun write operation and transfers the data to the second register. The bus agent is then allowed to retry the initial write operation, in response to which the first bridge circuit positively decodes the retried write operation and transfers the data to the first register. Thus, coherency is preserved between the first and second registers.

Abstract: A computer system having separate, yet compatible DMA controllers on a bus. Each DMA controller for controlling at least one DMA channel, each DMA controller having an independent set of registers for performing DMA operations and a configuration register for indicating channel status and designation. A DMA master for compatibly communicating with a processor and for initializing and communicating with the multiple DMA controllers.

Abstract: An arbitration scheme for a computer system having multiple arbiters for arbitrating access to a plurality of buses. In the preferred embodiment, a computer system is divided into a detachable laptop portion and an expansion base unit coupled through a shared PCI bus. Each of the two portions of the computer system includes separate PCI arbitration circuitry for arbitrating requests for the PCI bus from potential PCI and ISA bus masters. Included within the laptop portion of the computer system is a top level arbiter that determines whether the PCI arbiter in the laptop or expansion base unit has access to the PCI bus. Either PCI arbiter normally must receive a grant from the top level arbiter before it runs a cycle. While the laptop computer is docked, the top level arbiter selects between the PCI arbiters on an essentially time multiplexed basis. While the expansion base and laptop computer are undocked, the top level arbiter grants bus access to the laptop PCI arbiter.

Abstract: A multiple use core logic chip set is provided in a computer system that may be configured either as a bridge between an accelerated graphics port ("AGP") bus and host and memory buses, as a bridge between an additional registered peripheral component interconnect ("RegPCI") bus and the host and memory buses, or as a bridge between a primary PCI bus and an additional RegPCI bus. The function of the multiple use chip set is determined at the time of manufacture of the computer system or in the field whether an AGP bus bridge or an additional registered PCI bus bridge is to be implemented. The multiple use core logic chip set has an arbiter having Request ("REQ") and Grant ("GNT") signal lines for each PCI device utilized on the additional registered PCI bus. Selection of the type of bus bridge (AGP or RegPCI) in the multiple use core logic chip set may be made by a hardware signal input, or by software during computer system configuration or power on self test ("POST").

Abstract: A distributed direct memory access (DMA) architecture where greater than seven DMA channels are provided and utilized. Alternative methods are disclosed for paging or swapping DMA channels so that more than seven may exist in a computer system, but only seven may be available at a time to remain compatible with conventional DMA controller software. In one method, channels may be assigned identical addresses, with one enabled at one time. In another method, channels are assigned unique addresses but the DMA master addresses only a subset of the total number of channels so that up to seven are available to compatible software at any one time.

Abstract: 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.

Abstract: A distributed direct memory access (DMA) architecture where DMA controllers are modified to create isolated DMA channels. Each isolated channel includes its own set of uniquely addressable registers which provide functional compatibility with conventional DMA controllers. A DMA master interacts compatibly with the computer system and transparently communicates special cycles to the isolated DMA channels to cause the distributed DMA architecture to appear as the DMA controllers. The DMA master spawns special cycles to the isolated channels for sharing common write data with multiple channels and merging read data into a single DMA controller compatible register. Channel 4 cascading is also handled via tracking registers and special cycles to maintain disable and masking functionality of channel 4 as it effects channels 0-3.

Abstract: The present invention relates to a system and method for shadowing data of a first register and a second register of a computer system that share a common address. When a bus agent runs a write operation to the register address, retry logic of a first bridge circuit retries the write operation and masks access by the bus agent to the bus. Retry bus master logic reruns the write operation, in response to which the second bridge circuit subtractively decodes the rerun write operation and transfers the data to the second register. The bus agent is then allowed to retry the initial write operation, in response to which the first bridge circuit positively decodes the retried write operation and transfers the data to the first register. Thus, coherency is preserved between the first and second registers.

Abstract: 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.

Abstract: A computer system having separate, yet compatible DMA controllers on a bus. Each DMA controller for controlling at least one DMA channel, each DMA controller having an independent set of registers for performing DMA operations and a configuration register for indicating channel status and designation. A DMA master for compatibly communicating with a processor and for initializing and communicating with the multiple DMA controllers.

Abstract: A distributed direct memory access (DMA) architecture where greater than seven DMA channels are provided and utilized. Alternative methods are disclosed for paging or swapping DMA channels so that more than seven may exist in a computer system, but only seven may be available at a time to remain compatible with conventional DMA controller software. In one method, channels may be assigned identical addresses, with one enabled at one time. In another method, channels are assigned unique addresses but the DMA master addresses only a subset of of the total number of channels so that up to seven are available to compatible software at any one time.