A magnetic memory board was designed and an experimental model was constructed for evaluation of its characteristics. the memory board contains eight 256 kb memory chips with an 8 μm cycle and operates with a rotating magnetic frequency of 312.5 kHz. These chips are driven by an already-developed single-chip memory module and a high-speed rotating magnetic field drive circuit. to improve the peripheral circuits with respect to speed, reliability and size, several circuits were developed, including the transformer-coupled pulse-current generator for the functional part of the chip, the sense circuit with a high-sensitivity comparator, and the high-speed defect loop skip circuit using ROM and a shift resistor. the eight memory modules and their peripheral circuits were implemented on a 24.5 × 48.5 cm memory board. the circuits were adjusted and an examination was made of the defect loop detection and the operational margin, which indicated that stable operation was possible. Evaluation of the experimental memory board over a temperature range of 10° to 45° showed that the bias margin is larger than ±5 Oe, the rotating magnetic field amplitude margin is larger than ±6 Ue, and the pulse current phase margin is greater than ±150 as. the memory board was applied to the 64 Mb file in the database machine.
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