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. 02, 1994
Filed:
Aug. 29, 1991
Hitachi, Ltd., Tokyo, JP;
Abstract
A region comprising a plurality of real pages in a part of a real storage unit is provided with a first key storage unit having a plurality of key storage entries each corresponding to one of the plurality of real pages, while a second region comprising a plurality of real pages in the second part of the real storage unit is provided with a second key storage unit having a single key storage entry. When a real address designated by an instruction to be executed belongs to the first region, an entry corresponding to this address is accessed by a storage protection control circuit. When this address belongs to the second region, the second key storage unit is accessed irrespective of the address. Further, a key within the accessed key information is compared with a key on a program status word (PSW) allocated to a program to determine whether the execution of the instruction is permitted.