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:
Feb. 20, 1990
Filed:
Nov. 12, 1987
Merle E Houdek, Rochester, MN (US);
David O Lewis, Rochester, MN (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
Storage addressing error detection circuitry detects addressing errors in a computer system during data transfers between an I/O unit and main storage where main storage has logical boundaries which if crossed can cause destruction of data. The central processing unit (CPU) of the computer system furnishes the I/O unit the starting address for the data transfer and thereafter the I/O unit furnishes addresses for completion of the data transfer. The starting address contains a hash value related to the logical boundaries. Each time the I/O unit presents an address with a hash value for a data transfer another hash value is generated from the remainder of the address passed by the I/O unit. If the two hash values do not compare equal, a logical boundary in main storage would be crossed and to prevent such an occurrence the storage operation is inhibited and an error signal is sent to the I/O unit which then terminates the data transfer. A write to a read only storage area is also detected as a storage addressing error. A write hash is a read hash inverted. The read hash would not compare equal to the write hash and an error signal would be generated and sent to the I/O unit if the I/O unit were attempting to write into a read only storage area.