Apparatus for protecting memory storage blocks from I/O accesses
US5900019A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 23, 1996 |
| Grant date | May 4, 1999 |
| Priority date | — |
| Expiry date | May 23, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F12/1475
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Apparatus for protecting memory storage blocks (page frames) against unwanted I/O accesses, including I/O data transferred in an unwanted direction. I/O storage keys are provided in an I/O protection array. Each I/O key is comprised of one or two bits and is associated with a respective storage block in computer memory. If the array contains two bit I/O keys, each key has 4 settings for controlling I/O accesses to an associated storage block; which: 1) inhibit an I/O access in the input direction of I/O data flow, 2) inhibit an I/O access in the output direction of I/O data flow, 3) allow I/O accesses in both directions, or 4) prevent all I/O accesses. If the array contains single bit I/O storage keys, each key has two settings, which: 1) prevent all I/O accesses in the associated storage block, or 2) allow all I/O accesses in the associated block. No I/O program keys are needed for controlling this type of I/O protection, which avoids key comparison operations by the I/O access protection apparatus. Nevertheless, the use of the subject I/O protection apparatus does not prevent the use of apparatus for protecting the same storage blocks from unwanted accesses by central processors,…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.