Browse Prior Art Database

Forced Double Storage Operation

IP.com Disclosure Number: IPCOM000094131D
Original Publication Date: 1966-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 3 page(s) / 46K

Publishing Venue

IBM

Related People

Wissick, WP: AUTHOR [+2]

Abstract

Storage devices used in data processing systems have physical characteristics which require the construction of discrete independent units, insofar as the storage and retrieval of information is concerned. For instance, a pair of storage units, one containing even addresses and one containing odd addresses, is illustrated in the upper drawing. In order for a Central Processing Unit CPU to communicate with storage, it is necessary that it enter a request with a bus control unit BCU. From the addresses sent to BCU by CPU, BCU picks either the even or the odd storage unit then defines a particular internal address within the chosen storage unit. A problem arises when storage protection keys are stored either in an integral portion of the storage unit or in a subunit which is operated integrally with the storage unit.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 3

Forced Double Storage Operation

Storage devices used in data processing systems have physical characteristics which require the construction of discrete independent units, insofar as the storage and retrieval of information is concerned. For instance, a pair of storage units, one containing even addresses and one containing odd addresses, is illustrated in the upper drawing. In order for a Central Processing Unit CPU to communicate with storage, it is necessary that it enter a request with a bus control unit BCU. From the addresses sent to BCU by CPU, BCU picks either the even or the odd storage unit then defines a particular internal address within the chosen storage unit.

A problem arises when storage protection keys are stored either in an integral portion of the storage unit or in a subunit which is operated integrally with the storage unit. This is illustrated in the upper drawing by the portions of the storage devices marked Stg Prot.

Storage protection information relates to blocks of addresses, including both even and odd addresses. If the storage protection information is to be changed, it is necessary to change it in both the storage protection areas relating to the even storage unit and the comparable area relating to the odd storage unit. However, some devices have but a single storage unit, or storage units which are connected serially. In such devices, only one storage protection indication needs to be given in the average case. Thus different operation is required depending on how the storage units are arranged on a particular system. In order to make it possible for the program written for one system to run equally well on another system, assuming that they are comparable in size, etc., it is necessary that the instruction which permits changing the storage protection information in storage be the same. This requirement applies to either the single storage unit or the interleaved, even-odd, storage unit arrangement shown in the upper drawing.

Circuitry of the lower drawing can be utilized to permit interpreting a Set Key Instruction in such a fashion as to utilize the instruction twice, once for the even storage unit and once for the odd storage unit. When this instruction is given, if a CPU operation is involved and the storage has not been cancelled, And 1 sets trigger 2 so as to generate a signal which is used to block the storage accept signal from reaching CPU. The storage accept signal is a signal which indicates to the CPU that the storage request, in this case a set key instruction request,...