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Accommodation of Variable Length Records in a Collection of Bubble Chips

IP.com Disclosure Number: IPCOM000048091D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Chang, H: AUTHOR

Abstract

A technique is described for accommodating records of incremental or variable lengths in bubble chips wherein alignment of data items in different chips is obtained through the use of index loops and counters.

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Accommodation of Variable Length Records in a Collection of Bubble Chips

A technique is described for accommodating records of incremental or variable lengths in bubble chips wherein alignment of data items in different chips is obtained through the use of index loops and counters.

In available bubble memory chips, the basic unit of retrieval is of a fixed length (e.g., 32 bytes); i.e., 32 bytes are advanced in parallel to the transfer position, transferred from the minor loops into the major loop, and then read out serially, thus incurring a long delay. There are several trends conducive to a smaller unit of retrieval: (1) The resistance of a single replicate transfer line is too high, which results in a high voltage drop. Some manufacturers segment it into two. (2) A boot loop (or a few loops) is in common use which is retrieved separately from the data loops. (3) It has been advocated that columnized major/minor loops with multiple transfer lines are suitable for relational data base operations. Nevertheless, smaller units of retrieval still use fixed length records. Natural data comes in variable lengths. This discrepancy is resolved by the technique described below.

In the first generation of bubble products, this discrepancy simply does not arise. All records are serialized and packed into the bubble chips in 32-byte units, for example. The bubble controller during reading delivers data in bytes. This approach is consistent with the way data are stored and read from disks. However, this approach also deprives the user of the advantages intrinsic in bubbles, namely, more modular access and retrieval, and the capability of appending external intelligence to the data which is amendable to quick scan.

Two properties of bubble devices are to be utilized: (1) Th...