XBIOS is a term which describes a device driver shipped with many Ontrack products. It is a INT13 hooking device driver which accesses the AT ports directly. It provides all the INT13 opcodes defined in the original IBM AT BIOS in addition to many Ontrack proprietary commands. Some of these commands include a translator to access IDE drives larger than 528Mb, Read and Write Multiple, and IDE Identify to name a few.