Browse Prior Art Database

Interface Control Block for a Storage Subsystem

IP.com Disclosure Number: IPCOM000083167D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 62K

Publishing Venue

IBM

Related People

Callahan, RW: AUTHOR [+2]

Abstract

The following describes one way to represent a program or microprogram control block, called a "packet" within a storage subsystem of a data processing system. The figure depicts the fields within a packet, as follows: IID - A virtual address. This field has the sane fixed length in every packet. FLAG - Indicates whether the packet contains a fixed or variable number of member fields. This field has the same fixed length in every packet. NUMBER OF MEMBERS - Contains a number whose value is equal to the present number of member fields in the packet. This field has the same fixed length in every packet. CONSTRAINTS FIELD - A bit string with each bit corresponding to a particular member type. If the bit is 1, then that member type is allowed, if 0 it is not allowed.

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Interface Control Block for a Storage Subsystem

The following describes one way to represent a program or microprogram control block, called a "packet" within a storage subsystem of a data processing system. The figure depicts the fields within a packet, as follows:
IID - A virtual address. This field has the sane fixed length in every packet.

FLAG - Indicates whether the packet contains a fixed or variable number of member fields. This field has the

same fixed length in every packet.

NUMBER OF MEMBERS - Contains a number whose value is equal to the present number of member fields in the packet. This field

has the same fixed length in every packet.

CONSTRAINTS FIELD - A bit string with each bit corresponding to a particular member type. If the bit is 1, then that member

type is allowed, if 0 it is not allowed. This field has

the same fixed length in every packet and for expansion

purposes, contains a quantity of bits greater than the total

number of presently defined member types.

WRITE AUTHORITY QUANTITY - Contains a number whose value is equal to the number of IID's present in the Write Authority IID List.

This field has the same fixed length in every packet. If the

value stored is 0 than all packets have write authority.

WRITE AUTHORITY IID LIST - Contains a list of fixed length IID's which have authority to write into the members of this packet.

When the packet is initially created, this field can contain

any quantity of IID's. After generation, this field is fixed

in length for the life of each individual packet.

READ AUTHORITY QUANTITY - Contains a number whose value is equal to the number of IID's present in the Read Authority IID List.

This field has the same fixed length in every packet.

READ AUTHORITY IID LIST - Contains a list of fixed length IID's which have authority to read the members in this packet.

At creation of the packet this field can contain any quantity

of IID's. After generation, this field is fixed in length for

the life of each individual packet.

MEMBER TAG - One of these fixed length fields is needed for each member. The relative position of these fields indicates which

member they describe within the packet. Thus, the first Member

Tag pertains to the first member, second Tag to the second

member, etc. This Tag contains the attributes, such as

member type, necessary to describe the member. If the value

of the member is less than or equal to a predetermined

number of bytes, then the value itself is stored within this

Tag. Otherwise the Tag is a locator for the value and the

value itself is stored at another location.

The above fields are used and interpreted by a program processing subsystem (PPS) within the data processing system. The storage subsystem

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(SS) is the repository for this information. The interface between PPS and SS subsystems is defined so that requests for information from the PPS to the SS uses a general add...