"This BIOS feature controls the IDE controller's prefetch buffer. Whenever the processor requests for data from a drive, the IDE controller can prefetch the data following it. If the processor requests for the subsequent blocks of data, it can be quickly satisfied by the prefetched data.
This is especially useful if you do a lot of sequential data reads, like playing a music file or a video clip. By prefetching the following data blocks after each data request, the IDE controller can..."