摘要:
A method and apparatus of performing impedance compensation on signals on interfaces between chipset components is disclosed. In one embodiment, a present impedance adjustment value is generated, and a controlled impedance adjustment value is also established based on the present impedance adjustment value. Then a special cycle with a deterministic amount of time is generated to stabilize the interfaces. With the interfaces in a known state, the signals on the interfaces are updated with the controlled impedance adjustment value during the special cycle, where embodiment ensures the signals to be glitch-free.
摘要:
One embodiment of an apparatus for communicating routing and attribute information for a transaction between hubs in a computer system is disclosed. The apparatus includes a data path input/output unit to output a packet header for a transaction. The packet header includes a transaction descriptor routing field to identify an initiating agent that initiated the transaction. The transaction descriptor routing field includes a hub identification portion and a pipe identification portion. The hub identification portion identifies a hub that contains the initiating agent. The pipe identification portion further identifies the initiating agent within the identified hub if the transaction has no ordering requirements with respect to a second agent in the identified hub.
摘要:
An apparatus for arbitrating ownership of an interface between two hub agents is described. The apparatus includes a data path input/output unit to communicate with a data path and an arbitration circuit. The arbitration unit includes a least recently serviced status tracking circuit to determine which of the data path input/output unit and a device that transmits the second request signal has been granted ownership of the data path least recently, an arbitration signal output circuit to output a first request signal, and an arbitration signal input circuit to receive a second request signal. The arbitration unit grants ownership of the data path to the data path input/output unit when the first request signal is asserted if the second request signal is not asserted.
摘要:
A method and apparatus for queuing commands. An apparatus of the present invention utilizes one or more token queues and a storage block to avoid maintaining multiple separate queues and/or to facilitate reordering of queued elements. The apparatus includes at least one token queue and a token assignment circuit which queues a selected token in a token queue. A storage block stores an element in a slot corresponding to the selected token. One system employing the present invention includes a processor, a bus agent, a memory controller, and a main memory. The memory controller queues tokens representing received commands into appropriate command queues.
摘要:
A method and apparatus for ordering memory access commands. A command ordering circuit which is described includes a plurality of command slots which receive memory access commands. A page register stores a value indicating a last page accessed by a prior memory access command. Comparators compare the value in the page register to values stored in the command slots, and an arbiter receives outputs from the comparators and selects a command from one of the slots. According to the method described, memory accesses are reordered depending on the portion of memory accessed. A first memory access command requesting access to a first portion of memory is issued. Additional memory access commands also referencing the first portion of memory are issued until a count is reached. After the count is reached, a second memory access command which references a second portion of memory is issued.
摘要:
A method and apparatus for transferring data from a first bus to a second bus. A bridge couples a first bus to a second bus. The bridge includes a buffer to store two data elements of a first packet transferred to the buffer from the first bus. The bridge also includes a controller that permits a first data element to be transferred from the buffer to the second bus. In addition, if at least a portion of a second packet has not been transferred to the bridge from the first bus, then the controller causes at least one wait state to be inserted on the second bus before transferring the second data element of the first packet from the buffer to the second bus.