Browse Prior Art Database

Avoiding Stopping Tape for Creases

IP.com Disclosure Number: IPCOM000079366D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Current, HG: AUTHOR [+3]

Abstract

Creased tape continues to be a severe problem in magnetic tape handling devices. Such creases usually cause a stripe of an oxide layer on the tape to be completely removed across the width of the tape. When this occurs within a data block, it appears to the tape reading circuits as a reduction of readback signal amplitude similar to an end-of-record, or the onset of an interblock gap (IBG). Most crease avoidance techniques employed to date occur in the tape controller. This means that during crease detection and avoidance, the controller dedicates its operation to the tape unit in question. It is common practice to connect several tape units to a single controller. Hence, for crease avoidance purposes, an entire tape subsystem has been dedicated to that one problem.

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 53% of the total text.

Page 1 of 2

Avoiding Stopping Tape for Creases

Creased tape continues to be a severe problem in magnetic tape handling devices. Such creases usually cause a stripe of an oxide layer on the tape to be completely removed across the width of the tape. When this occurs within a data block, it appears to the tape reading circuits as a reduction of readback signal amplitude similar to an end-of-record, or the onset of an interblock gap (IBG).

Most crease avoidance techniques employed to date occur in the tape controller. This means that during crease detection and avoidance, the controller dedicates its operation to the tape unit in question.

It is common practice to connect several tape units to a single controller. Hence, for crease avoidance purposes, an entire tape subsystem has been dedicated to that one problem. An advantage to data processing is achieved when some crease avoidance can be accomplished within the tape unit.

A crease avoidance circuit for a tape unit includes a readback system signified by transducer 10 in operative relationship to magnetic tape 11. The output signals from the read apparatus are divided into three zones represented by three cables 12, 13, and 14. A plurality of OR circuits 15, 16, and 17, respectively, combine signals from each of the three zones 12, 13, and 14 into a single signal. The output of each of the OR's is combined in AND 18, in combination with a "not go" (stop) signal received from controller 20. A noise- rejection feature of OR's 15, 16, and 17 requires that no signals from any of the three areas be supplied, before a...