| BIOS settings | Basic Input Output Subsystem. Programmable chip that controls how information is passed to various devices in the computer system. A typical method to access the BIOS settings screen is to press ESC, F1, F2, F8, F10 or Del during the boot sequence. |
| boot priority | First device, or any device that is higher in the order list having preference over devices that are lower in the order. BIOS settings allow you to run a boot sequence from a floppy drive, a hard drive or a CD-ROM or a flash drive. You can configure the order in which your computer searches these physical devices for the boot sequence. For example, to boot from a CD-ROM drive instead of a hard drive, place the CD-ROM drive ahead of the hard drive in priority. |
| boot record | See MBR. |
| compressed cluster | Data that uses less disk space. When you set a file or folder property to compress data, the file or folder uses less disk space. While the size of the file is smaller, it must use a whole cluster in order to exist on the hard drive. As a result, compressed clusters contain "file slack space". This space may contain residual confidential data from the file that previously occupied this space. KillDisk can wipe out the residual without touching the existing data. |
| cluster | Logical group of disk sectors, managed by the operating system, for storing files. Each cluster is assigned a unique number when it is used. The operating system keeps track of clusters in the hard disk's root records or MFT records. (See lost cluster) |
| exclusive access | Lock that is applied to a partition for exclusive writing access, for example while recovering deleted or damaged files or folders. The recovery operation must have exclusive access to the target partition while recovering files. If another application or the operating system is using the target partition, you must close all applications or system processes that may be using the target partition before locking it. |
| FAT | File Allocation Table. File that contains the records of every other file and directory in a FAT-formatted hard disk drive. The operating system needs this information in order to access the files. There are FAT32, FAT16 and FAT versions. |
| free cluster | A cluster that is not occupied by a file's data. This space may contain residual confidential data from the file that previously occupied this space. |
| file slack space | Unused portion of a cluster. The smallest file (and even an empty folder) takes up an entire cluster. A 10-byte file will take up 2,048 bytes if that is the cluster size. This space may contain residual confidential data from the file that previously occupied this space. |
| deleted boot records | Damaged or erased MBR. In a damaged disk, if the location of the boot records is known, the partition table can be reconstructed. |
| hive | Highest level of organization in the Windows registry. At this level, system and local variables are stored. |
| ISO | Informal term for a disk image in the ISO 9660 file standard format. ISO 9660 file system is a standard, published by the International Organization for Standardization. It defines a file system for CD-ROM or DVD-ROM media that allows you to read the same CD or DVD whether you're on a PC, Mac, or other major computer platform. Making a disk image in the ISO 9660 file standard (an ISO image) is a common way to electronically store and transfer the contents of a hard drive. An ISO image often has the filename extension .ISO (although not necessarily), and is commonly referred to as an "ISO". |
| lost cluster | Cluster with an assigned number in the file allocation table, even though it is not assigned to any file. You can free up disk space by reassigning lost clusters. In DOS and Windows, you can find lost clusters with the ScanDisk utility. |
| MBR | Master Boot Record. All disks start with a boot sector. When you start the computer, the code in the MBR executes before the operating system is started. The location of the MBR is always track (cylinder) 0, side (head) 0, and sector 1. The MBR contains a file system identifier. |
| MFT records | Master File Table. File that contains the records of every other file and directory in an NTFS-formatted hard disk drive. The operating system needs this information to access the files. |
| root records | See FAT |
| SAM | Security Account Manager. Database stored as a registry file in Windows. It stores users' passwords in a hashed format. Since a hash function is one-way, this provides some measure of security for the storage of the passwords. |
| sector | Smallest unit that can be accessed on a disk. Sectors are segments within each track. |
| track | Circle of data around a disk. Tracks form concentric circles on a disk. |
| unallocated space | Space on a hard disk where no partition exists. A partition may have been deleted or damaged or a partition might not have been created. |
| unused space in MFT records | The performance of the computer system depends a lot on the performance of the MFT. When you delete files, the MFT entry for that file is not deleted, it is marked as deleted. This is called unused space in the MFT. If unused space is not removed from the MFT, the size of the table could grow to a point where it becomes fragmented, affecting the performance of the MFT and possibly the performance of the computer. This space may also contain residuals of the confidential data (file names, file attributes, resident file data) from the files that previously occupied these spaces. |