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In an effort to achieve higher data-rates in disk-drives, it has been proposed that moving the preamp closer to the head will improve writer performance. This paper will show that the opposite is true: moving the writer closer to the head degrades write current rise-time and overshoot. Although settling time is improved by moving the preamp closer to the head, impedance-matching techniques are sufficient to address this. Ironically, reader considerations may motivate Chip-On-Suspension (COS), but only for MR sensors that are either very high or very low impedance. This paper will detail the noise peaking that results from an impedance-mismatched reader input network. Both reader and writer performances can be improved by using novel architectures and by optimizing their respective interconnects. Index Terms--Bandwidth, disc-drive, disk-drive, head, impedance-matching, input-network, interconnect, MR, noise, preamp, reader, response, rise-time, writer.

In this article, we present an experimental study of the overwrite degradation in high speed recording. Recorded hard and easy transitions were directly characterized and correlated to medium speed, write current waveform and media properties. It has been found that, when high medium speed becomes greater than the bubble growth speed, the transition will be recorded when the field gradient is poor, which results in not only large hard transition shift, but also hard transition broadening. Slow field rise time causes further degradation due to the effective slowing down of the bubble growth speed. Write current overshoot can significantly suppress the degradation. Medium coercivity and its time dependence also have shown a direct effect on the overwrite degradation. Index Terms--Overwrite, high speed recording, rise time effect, current overshoot, time dependence of coercivity.

An obituary for physician Klaas Berend Klaassen is presented.