Browse Prior Art Database

Magnetically Actuated File Protect

IP.com Disclosure Number: IPCOM000077104D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Larson, DD: AUTHOR

Abstract

Previous file protects have been mechanical in nature, requiring at least one mechanical moving part for sensing presence or absence of the file protect indicator on a tape reel. Efficiency and reliability can be enhanced by substituting a retentive magnetic material on a tape cartridge or tape reel for indicating file protected record volumes.

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Magnetically Actuated File Protect

Previous file protects have been mechanical in nature, requiring at least one mechanical moving part for sensing presence or absence of the file protect indicator on a tape reel. Efficiency and reliability can be enhanced by substituting a retentive magnetic material on a tape cartridge or tape reel for indicating file protected record volumes.

Tape reel 10 has the usual wrap-around cartridge 12 protecting tape wound on the reel. Latch 11 can be of the type which is automatically openable by tape transport. Attached to the outer periphery of wrap-around cartridge 12 is a bar of retentive magnetic material 13. The axis of remanent magnetization of material 13 is parallel to the axis of rotation of spool 10. When placed in a tape transport, not shown, a particular orientation of the magnetization of material 13 is required to enable write status. Sensor 14 supplies a disable write signal to tape controls 15, thereby file protecting the records on the tape wound on spool 10. For example, if the remanent magnetization of material 13 has the proper pole adjacent to sensor 14, then sensor 14 enables writing. Alternatively, retentive magnetic bar 16 may be located adjacent the hub of reel 10. In this modification, removal of cartridge 12 from reel 10 does not remove the file protect.

The file protect can be automatically erased or imposed upon the record volume through a master control in a tape library system, for example. A magnetizi...