David's pointing you to the spec is an excellent answer. A few things I will add to the mix: * You will need multiple commands ( SECURITY ERASE PREPARE, SECURITY ERASE UNIT, and possibly other SECURITY commands ) from the spec in order to accomplish a secure erase. * Sending (single-sector) ATA passthru commands from uesr mode applications is possible on Windows (XP SP2 and newer, IIRC), assuming you have Admin privileges on the system. You will need do some Googling on IOCTL_ATA_PASSTHRU_DIRECT in order to find relevant information. * That being said, you will still be at the mercy of the system BIOS and possibly the O/S. Once a SECURITY FREEZE LOCK is sent to the drive, it is *generally* difficult or impossible to send SECURITY ERASE to the drive. Some motherboard BIOSs send the SECURITY FREEZE LOCK prior to start of boot just to ensure a drive is not accidentally or maliciously erased. All of this is from my memory, which is several years old at this point.
