The invention relates to a method of securing computer systems involving the logical containment of data. This efficient FIFO memory has two smaller standard single-port memory banks instead of one large dual-port memory bank, as in typical FIFO memories. A first generating device generates a transitional pattern including a support time data indicating a transition of support time and having a transition occurrence probability higher than a minimum occurrence probability in the pattern generation time-series data. A pressure plate is provided to carry out the pressure-contact or release of the driving clutch plates relative to the driven clutch plates.