The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 27, 2001
Filed:
Dec. 04, 1995
Michael J. Collins, Tomball, TX (US);
Michael P. Moriarty, Spring, TX (US);
John E. Larson, Houston, TX (US);
Jens K. Ramsey, Cypress, TX (US);
Compaq Computer Corporation, Houston, TX (US);
Abstract
A computer system including a memory controller provides a series of queues between a processor and a peripheral component interconnect (PCI) bus and a memory system. Memory coherency is maintained in two different ways. Before any read operations are accepted from the PCI bus, both of the posting queues must be empty. A write posting queue for processor to PCI writes must be flushed before a PCI device can access memory. If the queue is not empty when the PCI device requests a memory read, the PCI device is forced to retry the operation while the write posting queue is flushed. Also, while the queue is flushed, the processor is prevented from further posting to the queue. A timer provides a further temporary time that the processor is precluded from posting to allow enough time for the PCI master to retry the operation.