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:
Jul. 28, 1998
Filed:
May. 23, 1996
Paul Gregory Greenstein, Croton-on-Hudson, NY (US);
Richard Roland Guyette, LaGrangeville, NY (US);
John Ted Rodell, Wapplingers Falls, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
Main storage access protection against unwanted I/O accesses in storage blocks/page frames independent of any protection provided against unwanted CPU accesses. I/O programs are each assigned an I/O program key which is matched against an I/O storage key selected from an I/O storage protection array used only for protecting blocks from accesses by I/O programs, but not from any accesses by CPU programs. The address of each storage access request by an I/O program selects a key entry in the array containing the I/O storage key used in the comparison with the I/O program key. Each entry in the I/O storage array may also contain a second I/O storage key which may be either a one-bit type as described and claimed in application Ser. No. 08/652,197 or a two-bit type as described and claimed in application Ser. No. 08/652,079, both applications of which were filed on the same day as this application and assigned to the same assignee. CPU storage protection array is not required for I/O storage protection, but CPU storage protection may be added for protecting storage blocks against unwanted accesses by CPU programs. Either real or virtual CPU storage key protection may be added as compatible with the subject I/O storage protection arrangement. The separate I/O and CPU access protection functions may each include any or all of: write protection, read protection, and storage key protection for page frames.