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This copy o f the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without the author's prior consent. Hard disk drives function perfectly satisfactorily when used in a stable environment, but in certain applications they are subjected to shock and vibration. During the work reported in this thesis it has been found that when typical hard disk drives are subjected lo vibration, data transfer failure is found to be significant at frequencies between 440Hz and 700Hz, at an extreme, failing at only Ig o f sinusoidal vibration. These failures can largely be attributed to two key components: the suspension arm and the hard disk. At non-critical frequencies o f vibration the typical hard disk drive can reliably transfer data whilst subjected to as much as 45g. When transferring data to the drive controller, the drive's operations are controlled and monitored using BIOS commands. Examining the embedded erro