Browse Prior Art Database

Separate Store Protect and Fetch Protect

IP.com Disclosure Number: IPCOM000085799D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Boggs, JK: AUTHOR

Abstract

A separate fetch protect key is added to the program status word (PSW) to increase the flexibility of storage protection.

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Separate Store Protect and Fetch Protect

A separate fetch protect key is added to the program status word (PSW) to increase the flexibility of storage protection.

Up to this time, the PSW has included only a single key for providing storage protection. If the user had the key, he could either store into or fetch data from the protected area. If he did not have the key, he could not do either.

Increased flexibility can be obtained by modifying the PSW to include separate keys for the two functions. In particular, let the existing key provide the storing or writing protect function and add an additional key to the PSW to provide the fetching protect function.

The rules for allowing access for each of these keys can be the same as the existing rules for the single protection key. Also, there is no change in the number or size of the storage keys stored in memory. For any given partition in memory, one and the same storage key is used to service both functions. The only change is in the PSW.

Using this two-key technique, a user can be allowed to fetch data from a protected area and not be allowed to store data into this same area.

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