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Greased Tape Tolerance Checking

IP.com Disclosure Number: IPCOM000075788D
Original Publication Date: 1971-Nov-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 20K

Publishing Venue

IBM

Related People

Lutter, EP: AUTHOR [+2]

Abstract

One of the problems in magnetic tape subsystems is how well a subsystem, i.e., controller and tape drive (MTU), can handle a creased tape. Creased tape results in a dropout of the readback signal in all tracks. This dropout must be distinguished from an IBG (interblock gap) to ensure proper data processing operations.

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Greased Tape Tolerance Checking

One of the problems in magnetic tape subsystems is how well a subsystem,
i.e., controller and tape drive (MTU), can handle a creased tape. Creased tape results in a dropout of the readback signal in all tracks. This dropout must be distinguished from an IBG (interblock gap) to ensure proper data processing operations.

To test the tolerance of a tape subsystem, the subsystem is placed in the diagnostic mode. A tape mark (TM) is recorded on the media. Following TM, an IBG is generated; then, a data block is recorded beginning at 10 and extending through 11. Within the tape block, a creased tape simulation dropout is recorded in all tracks beginning at 12 and ending at 13. After the above-described pattern has been written, tape is positioned adjacent the transducer at IBG-2. Tape is then backspace record followed with a read backward. If a unit exception is supplied, the subsystem detected dropout 12, 13 as a creased tape dropout. However, if no unit exception was reported, tape drive stopped in the creased tape dropout, i.e., between 12 and 13. In the latter instance, tape subsystem was not capable of distinguishing between the creased tape dropout and the usual IBG.

The tolerance to the creased tape dropout can be detected by repeating the above tests with increasing lengths of creased tape dropouts, as indicated by the dotted lines. The simulated creased tape dropout is increased until the drive actually stops within the simulated...