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:
Aug. 15, 1989
Filed:
Jan. 29, 1986
Robert E Stewart, Stow, MA (US);
Paul J Natusch, Westford, MA (US);
Eugene L Yu, Groton, MA (US);
James B Keller, Arlington, MA (US);
Digital Equipment Corporation, Maynard, MA (US);
Abstract
In a data processing system in which access to a second unit by a first unit through a system bus is determined by an arbitration unit, when a requesting unit that receives access to the system bus is unable to use that access for interaction with the second unit, a busy signal is provided to the arbitration unit and to the units. The busy signal causes the units to reinstitute a request for access to the system bus when the subsystem had an aborted transaction. The busy signal enforces a delay in the next arbitration for the system bus until a unit, with an aborted transaction as a result of the busy signal, can reassert the request for access signal. Moreover, apparatus can be included with the arbitration unit that permits rearbitrating access to the bus using the priority conditions in effect at the time of the original arbitration.