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:
Apr. 20, 1999
Filed:
Jun. 30, 1997
Lawrence Joseph Powell, Jr, Round Rock, TX (US);
Krishnamurthy Venkatramani, Austin, TX (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A protocol and apparatus for crossbar switches where the cycle time is too short to allow the updating of the input/output buffer controls by the arbitration logic in one cycle. The crossbar switch has separate data paths and commands paths. Two types of commands are sent over the crossbar switches. The first type is an address (A) only command which consist of a single packet needing one clock cycle. The second type of command is an Address with Data command (AD), consisting of two through nine packets, and requiring a maximum of nine clock cycles. A command becomes a request through two different paths through the crossbar switch. The first path is via an input bypass path which allows an input command buffer to be bypassed and a request written directly to a multiplexer. The second path is through the input command buffer which is written but not selected until processing is completed for the previous command. The crossbar protocol allows a request to be accepted by writing information into the output buffers before the accept is available.