Magnetic bubble file memory using 256 KBIT chip

Several companies have recently begun to produce 256K-bit modules which use the 3μm bubble, but few papers have been published on bubble file memories that have been developed using these large capacity chips. We have designed, produced and tested an experimental bubble memory system with 256K-bit chip modules. This 55M-bit system consists of a controller, memory and power supply. System features are (1) 200kHz operation, (2) a transfer rate of 200K-bits/sec per chip, and (3) printed circuit board assembly which allows expansion in 4.6M-bit memory board groups. Each bubble memory module is a 20-pin dual-in-line package with one 256K-bit chip[1]. It has 264 minor loops of 1,070 bits each. A memory board group is made up of two memory boards with 10 of these 256K-bit modules, sensing circuits, function driver circuits, and PROMs for handling defective loops. There is also one driver board with the coil driver circuits. Tests on the experimental model with 55M-bit capacity show that this memory system operates reliably with a drive frequency of 200kHz. Average access time is approximately 5 msec, and transfer rate is 200K-bytes/sec. The result shows that a large-capacity bubble memory system can be applied to various systems as file memory.