Abstract: A synthetic adsorbent, where a maximum value of a differential pore volume under a pressure condition of 0.5 to 30.0 psia is greater than 0.05 mL/g. A method of measuring the differential pore volume includes reducing a pressure in a sample container where the synthetic adsorbent that has been dried is placed to 10 Pa or less, mercury is degassed by reducing the pressure to 10 Pa or less, and the sample container is filled with the mercury at a pressure of 0.5 psia, measuring a mercury intrusion amount when the pressure in the sample container filled with the mercury is increased from 0.5 to 30.0 psia, and calculating the differential pore volume by dividing an amount of an increase in the mercury intrusion amount when a first-stage pressure calculated based on the mercury intrusion amount measured in the measuring is increased, by a measured amount of the synthetic adsorbent.

Abstract: A flexible magnetic disc drive apparatus is provided in which access efficiency to a flexible magnetic disc is improved, and which enables rewriting alternate information in the case of alternate registration and allows access even if there is a defect in an ID field.