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. 03, 1984
Filed:
Feb. 11, 1981
Hitachi, Ltd., Tokyo, JP;
Abstract
A multiprocessor system includes a plurality of central processing units (CPUs), which have a main storage in common, and a key storage for storing therein control information for storage protection of, reference to, and change in the main storage. Each CPU is provided with the key storage, the CPUs are connected by interface lines so as to form a ring-like combination, a CPU in which a key access request is generated, carries out the key processing for its own key storage and supplies the interface line with an address, data and others which are contained in the key access request, and another CPU receives the address, data and others to perform the key processing for its own key storage. A signal for determining the priority among key access requests simultaneously generated in a plurality of central processing units circulates through the CPUs via the interface lines, one of the CPUs having generated the key access requests catches the priority determining signal to make its own key access request valid, and prevents the circulation of the priority determining signal for a time till the key processing based upon the valid request has been completed.