Browse Prior Art Database

Magnetic Tape Identification

IP.com Disclosure Number: IPCOM000086637D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Devore, EW: AUTHOR

Abstract

In automatic tape libraries such as shown in U. S. Patent 2,941,738, it is desirable that the magnetic tape unit receiving the magnetic tape record verify that the received tape is the one desired. In such automatic systems, the critical-path time is represented by a transfer of the magnetic tape record member from a storage compartment to the time the transducer in the magnetic tape unit is prepared for reading or recording data signals. To minimize this critical-path time, it is desirable to move promptly to the portion of the magnetic tape record containing the data signals to be read or having the area on which data signals are to be recorded.

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Magnetic Tape Identification

In automatic tape libraries such as shown in U. S. Patent 2,941,738, it is desirable that the magnetic tape unit receiving the magnetic tape record verify that the received tape is the one desired. In such automatic systems, the critical- path time is represented by a transfer of the magnetic tape record member from a storage compartment to the time the transducer in the magnetic tape unit is prepared for reading or recording data signals. To minimize this critical-path time, it is desirable to move promptly to the portion of the magnetic tape record containing the data signals to be read or having the area on which data signals are to be recorded. Therefore, during automatic loading, it is desirable that the tape, as it is loaded into the tape units, not stop until the desired transducing area on the tape has reached the transducer of the magnetic tape unit.

In magnetic tape records of the rotary-head type, the tape record has a pair of servo tracks with record-track identifying signals. Such track identifying signals can be of the multifrequency type, such as indicated in the signal format labeled "servo". In that format, a predetermined number of cycles of signals at frequency F1 bracket an indicating signal F2. F2 is a signal of one or more cycles having a distinctly different frequency than F1. By timing the relationship between these two signals, a record track can be precisely located with respect to a scanning head. In accordance with this technique, the servo signals can be adjusted to indicate a serial number (SN) of the record member. For example, in some tape records, a visual SN is hot-stamped on the free end of the record tape. This same serial number is recorded in the servo tracks, as in the hatched areas, preferably at the beginning of tape B0T and at predetermined spaced positions along the tape length. Accordingly, when the tape is loaded into the tape unit, it can be moved rapidly to one of the areas identifying the record member. The serial number can be read from the servo areas and verified against the requested number. Since the record tracks are close to such areas, total tape-transport time can be minimized. That is, as the data area is being approached, the tape would be normally slowed down to assure accurate positioning. During this slowdown period, the tape serial numbers can be read on the fly.

The tape serial numbers can be encoded by any modulo cod...