Two-year running operation tests for magnetic bubble memory

Results of two-year memory operation tests using a 0.5-Mbit capacity, 2.5-ms access-time prototype bubble memory, which has been operated since 1975, are described. During the memory operation tests, as a data longevity evaluation, failure rates under various kinds of memory operation modes were estimated. No deviation in bias field margin and chip control function margins were observed, when compared with the initial margins. These results confirm that the memory has the high data longevity and reliability required for use as practical solid state file.