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Non Destructive Readout for Core Memory

IP.com Disclosure Number: IPCOM000096493D
Original Publication Date: 1963-Jun-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Poglia, HR: AUTHOR

Abstract

Non-destructive readout of a magnetic core is obtained by first applying a predisturb pulse to the core. This pulse is of sufficient amplitude and duration to partially switch 10% to 30% of the flux, if the core is in its 1 state (note hysteresis loop), and no flux if the core is in its 0 state. The resulting partially switched state of the core which exists if it was initially in its 1 state is the predisturbed or 1 state. The predisturb pulse is immediately followed by a non-destructive readout NDRO pulse.

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Non Destructive Readout for Core Memory

Non-destructive readout of a magnetic core is obtained by first applying a predisturb pulse to the core. This pulse is of sufficient amplitude and duration to partially switch 10% to 30% of the flux, if the core is in its 1 state (note hysteresis loop), and no flux if the core is in its 0 state. The resulting partially switched state of the core which exists if it was initially in its 1 state is the predisturbed or 1 state. The predisturb pulse is immediately followed by a non-destructive readout NDRO pulse.

Due to the relaxation effect which is in existence at the time the NDRO pulse is applied to the core and to the fact that the 1 state is not one of the two major remanent states of the core, the threshold field of the core in its 1 state is relatively low. Thus, rapid switching, positive restoration, and a relatively large sense signal are obtained with a smaller NDRO drive pulse than was previously required. The small NDRO drive pulse is not sufficient to overcome the high threshold field which exists if the core is in its 0 state. Therefore, by utilizing the relaxation effect, rapid non-destructive readout of a core with large amplitude signals is obtained with a low-current drive pulse.

This technique can be employed either with 2-D or 3-D memory arrays. With a 2-D array, the readout waveform shown is applied to the word line. With a 3-D array a half-predisturb pulse and a half-NDRO pulse are applied to the X drive l...