Intelligent magnetic bubble memories
ISCA '78 Proceedings of the 5th annual symposium on Computer architecture
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Bubbles have several attractive characteristics which could lead to major use of bubble memories in future computer systems. Being block-organized memories, fundamental improvements will be necessary to reduce the mean access time and increase the data transfer rate. Organizations of permal-loy bar memories are presented, in which two basic techniques are available for providing bubble propagation: 1. Field-access (simple structure and slow propagation). 2. Current-access (complex structure and fast propagation). All classical organizations are based on field-access technique whose limited frequency imposes many restrictions on maximum chip capacity and performance.A family of new organizations is proposed, based on a combination of the two techniques: field-access for “storage register” and current-access for “access register” shifting. Access register bits are themselves part of storage registers, avoiding use of transfer gates and useless data alignment in access registers. Multiple access registers are permitted in the chip to give simultaneous access to many bits. Start-stop capability and bidirectional shifting of bubbles are exploited in the new organizations.