Dynamic Drive Overlay

From Wikipedia, the free encyclopedia

Dynamic Drive Overlay (DDO, also referred to as: software translation driver) is a software technique to extend a system BIOS that does not support Logical Block Addressing (LBA) to access drives larger than 538MB. The technology was continued with similar types of problems up to the LBA-48 extension.

This technique overrides some of the motherboard BIOS' hard disk controller driver in RAM. To allow access to the full size of any hard disk the software must be loaded before other programs try to access the upper parts of a disk with a critical size. To ensure that this extension gets loaded early most often the boot disk's master boot record is modified and the software installed at the beginning of the disk.

The most wide spread vendor for such an extension is the company Ontrack which is licensing its DDO component to several of the major harddisk vendors for integration into their management tools and into their products.