Characterization and test results for a 272K bubble memory package

A magnetic bubble memory package has been designed specifically as a serial data store for use in a voice synthesis system. The memory package contains four 68,121 bit serial shift-register chips for a total capacity of 272,484 bits. One such package, operating at a 24 kHz data rate, can provide 12 seconds of speech. Each 5 mm by 6 mm bubble chip consists of a single 68,121 bit shift register, data replicator, expander active and dummy detector, and nucleate generator. A garnet composition with nominally 3 μm bubbles was selected because its bubble-collapse-field temperature coefficient -0.2%/°C accurately tracks that of Indox over the required 10°C to 60°C temperature range. The nominal in-plane fields are 40 Oe amplitude at a frequency of 48 kHz. The bubble chips and the packages used in this study were fabricated in a Device Capability Line at the Reading Western Electric Facility.