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. 17, 1999
Filed:
Jan. 07, 1997
Michael J Heideman, New Brighton, MN (US);
Thomas P Cooper, New Brighton, MN (US);
Unisys Corporation, Blue Bell, PA (US);
Abstract
A computer system having dual outboard devices for generating audit trail sequence numbers and performing file locking. One embodiment includes a master and a slave outboard device, where lock request handling includes a lock request first sent to the master, lock grant awaited, followed by a request sent to the slave. Unlock request handling includes sending an unlock request to slave first, followed by sending an unlock request to the master. Obtaining a system sequence number includes always reading the slave outboard device, then reading the master outboard device. The computer system includes a method for switching host processors from a single outboard device mode to a dual outboard device mode and back again in the event of failure of one of the outboard devices.