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Redundancy Scheme for Major Minor Loop Bubble Memories

IP.com Disclosure Number: IPCOM000084164D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Lin, YS: AUTHOR [+3]

Abstract

Redundancy is important to obtain reasonably good yield in bubble domain memory organizations. Generally, redundant elements are placed on the bubble domain chips so that defective elements may be replaced by these redundant elements. A redundancy technique for a major/minor loop memory organization is described, which does not disturb the synchronous operation of the major/minor loops.

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Redundancy Scheme for Major Minor Loop Bubble Memories

Redundancy is important to obtain reasonably good yield in bubble domain memory organizations. Generally, redundant elements are placed on the bubble domain chips so that defective elements may be replaced by these redundant elements. A redundancy technique for a major/minor loop memory organization is described, which does not disturb the synchronous operation of the major/minor loops.

A spare minor loop is provided for each group of k minor loops and means are provided to use the (k-1) good minor loops, without disturbing synchronous operation of the memory organization. Fig. 1a shows a diagram of the arrangement in which the dotted lines between the major loop and the minor loops indicate possible transfer paths between them. Assuming that testing indicated that minor loop 3 was defective, the arrangement shown by solid lines in Fig. 1b is used to skip the defective loop.

The major/minor loop chip layout is shown in Fig. 2, while Fig. 3 shows a detailed diagram of a portion of the chip layout. In particular, the transfer gate for achieving the skipping of a defective minor loop is indicated. Normal translation from major to minor loops:.

During the rotating field cycle 2-->3, the transfer line is energized by sending a current I through the line. With the help of magnetic poles 2,3 created in minor loop 4, bubbles in the major loop are transferred toward position 3 of minor loop
4. This is the normal trans...