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Device configuration overlay (DCO) is a hidden area on many of today's hard disk drives (HDDs). Usually when information is stored in either the DCO or host protected area (HPA), it is not accessible by the BIOS (or UEFI), OS, or the user. However, certain tools can be used to modify the HPA or DCO.
Pre-boot authentication can by performed by an add-on of the operating system like Linux Initial ramdisk or Microsoft's boot software of the system partition (or boot partition) or by a variety of full disk encryption (FDE) vendors that can be installed separately to the operating system. Legacy FDE systems tended to rely upon PBA as their ...
A file containing such contents is sometimes termed "a BIOS image". A BIOS might be reflashed in order to upgrade to a newer version to fix bugs or provide improved performance or to support newer hardware. Some computers also support updating the BIOS via an update floppy disk or a special partition on the hard drive. [57]
chntpw has no support for fully encrypted NTFS partitions (the only possible exceptions to this are encrypted partitions readable by Linux such as LUKS), usernames containing Unicode characters, or Active Directory passwords (with the exception of local users of systems that are members of an AD domain). The password changing feature is also ...
Authentication on power up of the drive must still take place within the CPU via either a software pre-boot authentication environment (i.e., with a software-based full disk encryption component - hybrid full disk encryption) or with a BIOS password. In additions, some SEDs support IEEE 1667 standard. [2]
INT 13h is shorthand for BIOS interrupt call 13 hex, the 20th interrupt vector in an x86-based (IBM PC-descended) computer system.The BIOS typically sets up a real mode interrupt handler at this vector that provides sector-based hard disk and floppy disk read and write services using cylinder-head-sector (CHS) addressing.
BIOS interrupt calls perform hardware control or I/O functions requested by a program, return system information to the program, or do both. A key element of the purpose of BIOS calls is abstraction - the BIOS calls perform generally defined functions, and the specific details of how those functions are executed on the particular hardware of the system are encapsulated in the BIOS and hidden ...
The HPA is useful only if other software or firmware (e.g. BIOS or UEFI) is able to use it. Software and firmware that are able to use the HPA are referred to as 'HPA aware'. The ATA command that these entities use is called READ NATIVE MAX ADDRESS. This command accesses a register that contains the true size of the hard drive.