Embodiments relate to a computer system for bitline deletion, the system including a cache controller and cache. and a latex of a polymer of vinyl acetate having a dry Tg above room temperature but a Tg when wet below 23 C. Register 30 is driven by a frequency-divided clock signal obtained by dividing the frequency of the clock signal at a predetermined frequency division rate. The invention also discloses a disk drive unit having the HGA.