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:
Oct. 01, 1991
Filed:
Mar. 28, 1989
Eugene Nusinov, Sharon, MA (US);
Thomas F Joyce, Westford, MA (US);
Bull HN Information Systems Inc., Billerica, MA (US);
Abstract
A segment descriptor unit (SDU) includes a divided random access memory (RAM), a content addressable memory (CAM) and decoder circuits interconnected for performing dynamic and static address translation operations within a minimum of chip area and power. The CAM is arranged to store a number of entries which include segment number and validity information associated with a corresponding number of segment descriptors. The RAM contains locations allocated for storing segment descriptor words (SDW's) and working data. Each SDW is logically divided into two fields, a static translation word (STW) field containing all of the bits required for performing a static address translation operation and an access control word (ACW) field containing all of the bits required for verifying compliance with system security. The bits of each STW and ACW are stored in alternate bit positions of the SDW locations. Each pair of RAM bit locations couple to a common read/write amplifier and multiplexer circuit. Through the use of microinstruction commands coded to specify different address translation functions, the STW and ACW fields selected by the CAM are read out from RAM during different intervals for carrying out the steps of those operations.