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Write Compensation for Head Gap Scatter

IP.com Disclosure Number: IPCOM000073637D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Niccore, FW: AUTHOR

Abstract

This circuit provides manually adjustable delay for each track of the multitrack NRZI data to be written on magnetic tape by a multigap head, the individual gaps of which may not be in exact transverse alignment to the path of the tape, due to either head gap scatter or to mechanical misalignment of the head relative to the tape path. One of these circuits is utilized for each track of data. The amount of delay selected for each track is such as to write all data transitions of a given data byte perpendicular to the direction of tape travel. The NRZI write input data A of a track is applied to the input of an inverting Exclusive OR 1. DC trigger 2 has been reset by E such that its output B is initially at the same state as data A. Thereafter, resetting is not required.

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Write Compensation for Head Gap Scatter

This circuit provides manually adjustable delay for each track of the multitrack NRZI data to be written on magnetic tape by a multigap head, the individual gaps of which may not be in exact transverse alignment to the path of the tape, due to either head gap scatter or to mechanical misalignment of the head relative to the tape path. One of these circuits is utilized for each track of data.

The amount of delay selected for each track is such as to write all data transitions of a given data byte perpendicular to the direction of tape travel. The NRZI write input data A of a track is applied to the input of an inverting Exclusive OR 1. DC trigger 2 has been reset by E such that its output B is initially at the same state as data A. Thereafter, resetting is not required. The output C of the Exclusive OR is high when inputs A and B have the same state, and is low when inputs A and B are of different states. When input data A changes state, output C becomes low, and output D of monostable multivibrator 3 assumes its unstable state 4 for a time period T, the length of which is determined by the values of capacitor 5 and resistor 6. The trigger changes state only on a negative-going transition of D, thus, when output D falls at the end of time T, trigger 2 changes state, causing 8 to fall, this, in turn, causing C to rise. On the next transition of input data A, the cycle repeats.

B is thus a reproduction of A, delayed by the tim...