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Mechanism to Control Data Transfer Between External and Main Storage

IP.com Disclosure Number: IPCOM000085122D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Coleman, CD: AUTHOR [+3]

Abstract

For data security purposes, it may be important to require that the transmission of information from or to predefined areas of external storage can occur only to or from certain predefined areas of main storage.

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Mechanism to Control Data Transfer Between External and Main Storage

For data security purposes, it may be important to require that the transmission of information from or to predefined areas of external storage can occur only to or from certain predefined areas of main storage.

It is required that the different functional information areas of main storage be segregated and labeled. The labeling can be an extension to the storage key. The number of bits required for this labeling depends on the number of data types to be distinguished, i.e., log n bits for n data types.

The first part of the mechanism consists of a way of performing a similar labeling of functional data types on external storage, i.e., an external key. Each record of external storage is categorized by a new byte added to the count field. The number of bits of this type used for this identification depends on the number of categories to distinguish, i.e., log m bits for m external data types.

Then a matrix is constructed that has as rows the main storage data types, as columns the external storage categories, and as entries the permitted type of action from main storage into external storage (read, write, or variations thereof). This matrix can be seen as an elementary type of access matrix.

Finally, the enforcement of the transmission rules defined by the matrix is performed by a simple logic circuit (combinational or sequential), whose inputs are the external key bits, the internal data labelin...