Ranges for C/H/S (Cylinders/Heads/Sectors) adressing of a PC's IDE/ATA hard drive - useful if (for example) you emulate PCs/compatibles with something like bochs/plex86 (freemware):

The maximum parameter values accepted by the original int-13h BIOS routines for accessing the hard drive are 1024 for cylinders*, 256 for heads, and 63 for sectors. At 512 bytes per sector, this gives a maximum addressable disk capacity of [1024 * 256 * 63 * 512 =] 8,455,716,864 bytes (8.4 GB/7.875 gibibytes).

Certain actual (ATA) drives at the time were using translation mechanisms targetted at 16383 cylinders, 16 heads, and 63 sectors per track - which (note 1024*256/16 = 16384) also achieves an 8.4 gigabyte capacity. Subsequently, there is a combined limit at 528MB (504 MiB) in BIOSes that predate Logical Block Address (LBA) translation, since 1024/16/63 = 528,482,304 bytes.

Modern drives (larger than 8.4GB) cannot be accessed by the regular (read "legacy", if you'd rather) BIOS routines, so the drives specify the capacity 16383/16/63 to the BIOS, thereby communicating to the OS that it needs to use the "extended int 13h" routines to determine the true physical drive size.

(*Presumably the reason certain LILO versions complain about certain sizes of hard drive/partition arrangements)