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Eliminating Skew in Magnetic Films

IP.com Disclosure Number: IPCOM000091319D
Original Publication Date: 1968-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Ainslie, NG: AUTHOR [+2]

Abstract

Magnetic film storage elements functioning in the orthoganol-field, rotational switching mode normally experience only unipolar hard axis word pulses. During a destructive readout DRO operation, the information state of the device is read by sensing the flux change during the rise of this word pulse whose amplitude must exceed the anisotropy field Hk. While the word pulse is still on, the device is rewritten by applying an easy axis bit pulse whose polarity is determined by the sign of the information that is intended, i.e., a 1 or 0. The bit pulse remains on for a time after the word pulse falls. Thus the readwrite sequence in a DRO operation normally consists of unipolar word pulses and overlapping bit pulses of either polarity as in drawing 1.

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Eliminating Skew in Magnetic Films

Magnetic film storage elements functioning in the orthoganol-field, rotational switching mode normally experience only unipolar hard axis word pulses. During a destructive readout DRO operation, the information state of the device is read by sensing the flux change during the rise of this word pulse whose amplitude must exceed the anisotropy field Hk. While the word pulse is still on, the device is rewritten by applying an easy axis bit pulse whose polarity is determined by the sign of the information that is intended, i.e., a 1 or 0. The bit pulse remains on for a time after the word pulse falls. Thus the readwrite sequence in a DRO operation normally consists of unipolar word pulses and overlapping bit pulses of either polarity as in drawing 1.

In the case of nondestructive readout NDRO operation, the write process is much like that for the DRO operation except that the read process consists of an arbitrary long sequence of low amplitude word pulses used for the write process where the amplitude must exceed the anisotropy field Hk. The low amplitude interrogating pulse in NDRO operations must be less than Hk as in drawing 2.

At certain times during these DRO and NDRO pulse sequences, the tendency to skew is very great. In particular, this occurs when the magnetization lies at angles other than 0 degree or 90 degrees to the bit-field direction. Such is the case, for example, during the time that the word and bit pulses overlap...