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Browse Prior Art Database

Memory Drive Arrangement

IP.com Disclosure Number: IPCOM000094521D
Original Publication Date: 1965-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Crawford, DJ: AUTHOR

Abstract

In flat film memories where a magnetic memory element 10 is supported by a conductive ground plane 12, the phenomenon of circulating ground plane currents occurs. Specifically, over a number of cycles of operation, a circulating current is built up in ground plane 12 as a result of repeated applications of like polarity drive pulses to drive line 14. This phenomenon generally degrades the overall operation of the memory.

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Memory Drive Arrangement

In flat film memories where a magnetic memory element 10 is supported by a conductive ground plane 12, the phenomenon of circulating ground plane currents occurs. Specifically, over a number of cycles of operation, a circulating current is built up in ground plane 12 as a result of repeated applications of like polarity drive pulses to drive line 14. This phenomenon generally degrades the overall operation of the memory.

One solution to this problem is to follow each drive pulse with an equal and opposite polarity drive pulse to preclude there being any net DC component buildup in ground plane 12. This capability is provided by double-bit pulse generator 16. It is not essential to add a cancelling drive pulse during every memory cycle. Such is due to the fact that the time constants involved with respect to ground plane 12 require a number of successive bit pulses of the same polarity before the circulating current buildup is large enough to cause harm. Therefore, a single drive pulse generator 18 is normally operated except when an Undue circulating current buildup is sensed. At this time double drive pulse generator 16 is operatively energized.

To determine when the level of circulating current in ground plane 12 becomes excessive, an RC network 20 is attached to each memory drive line, e.
g., 14. The time constant of each RC network is set to closely approximate the time constant of ground plane 12, thus allowing the charge buildup on...