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[ The PC Guide | Systems and Components Reference Guide | Hard Disk Drives | Hard Disk BIOS and Capacity Factors | Hard Disk BIOS Translation Modes ]

Comparison of Translation Modes

The table below shows how the three translation modes compare. This is done by showing a summary of the different modes used in the overall path from the operating system, through the BIOS, to the hard disk controller, to the physical drive platters:

Interface

Standard CHS

Extended CHS (ECHS) / Large

Logical Block Addressing

Physical Drive Platters to Integrated Disk Controller

Physical Geometry

Physical Geometry

Physical Geometry

Integrated Disk Controller to BIOS

Logical Geometry

Logical Geometry

Logical Block Address

BIOS to Operating System and Applications (through Int 13h)

Logical Geometry

Translated Geometry

Translated Geometry

Notice how in all three schemes the physical geometry is hidden within the hard disk itself. In the case of LBA, the logical geometry is presented to the BIOS only so it can be translated for use by the operating system; communication between the BIOS and the hard disk controller occur using the logical block address.

For modern drives that use Int13h extensions, only logical block addressing is used.

Next: Caveats on Changing Translation Modes and Transferring Hard Disks Between PCs


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