Maintaining Sorted Files in a Magnetic Bubble Memory

A typical organization of magnetic bubble memories is the major-minor loop structure, where n (minor) loops are connected via switches to another (major) loop, containing the I/O station. We work on a sorted file F, split into subfiles allocated in the minor loops. Two schemes of operation are proposed, called the linear scheme and the tree scheme. In both cases the subfiles are maintained sorted, and constitute consecutive sections of F in the linear scheme, and nodes of a binary search tree for F in the tree scheme. The main operation examined is the insertion of a new record in F. Algorithms are given to execute such an operation in the two schemes and their performance is analyzed. Other operations are also briefly discussed. A comparison between the two schemes on the basis of time needed for the different operations, memory occupation, and hardware requirements, shows advantages of one or the other, depending upon the evaluation criteria. Copyright © 1980 by The Institute of Electrical and Electronics Engineers, Inc.