In the early days of PCs, harddisks.

[bart de troyer]

Unfortunately, there is no way to address large harddisks (more than 8GB to be 
precise) with CHS addresses. The so called BIOS extensions must be used to 
access large harddisks. Of course these BIOS extensions are available only for 
new mainboards. These extended BIOS functions address harddisks simply with 
block numbers (LBA, logical block address). As you will probably expect it, 
most operating systems use the old CHS addressing methods in their early boot 
phases.

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