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Browse Prior Art Database

Tape Record Accessing

IP.com Disclosure Number: IPCOM000084564D
Original Publication Date: 1975-Dec-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Irwin, JW: AUTHOR [+2]

Abstract

In automatic tape libraries where a plurality of tape cartridges (volumes) are automatically transported to any one of a plurality of tape recorders, it is highly desirable that before data exchanges occur, the volume number of the transported cartridge be verified. This can be done at the leader portion of the tape after automatically threading the tape into the tape recorder. This action, however, requires additional time thereby increasing the access time to a given record by up to one-half second.

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Tape Record Accessing

In automatic tape libraries where a plurality of tape cartridges (volumes) are automatically transported to any one of a plurality of tape recorders, it is highly desirable that before data exchanges occur, the volume number of the transported cartridge be verified. This can be done at the leader portion of the tape after automatically threading the tape into the tape recorder. This action, however, requires additional time thereby increasing the access time to a given record by up to one-half second.

The stop at the leader portion of the tape medium can be obviated by recording the volume number in each of the individual record portions of the tape medium. Since media cost in tape is relatively inexpensive, repeated recording adds insubstantial cost to the total storage cost while enhancing access time, thereby reducing access costs.

In the drawing, each portion of volumes XXX and XXY is divided into a like number of record areas denoted R1012-R1016. In addition to the record number being recorded with each of the record areas, the respective volume number is recorded along with the record identifying number. Operation of the tape library then permits tachometer positioning of the tape immediately following automatic threading, without stopping or otherwise sensing record signals on the media to position X for accessing record R1015. When the record areas are of fixed length, the tachometer position for each of the records is predefined ena...