VI.  Back matter

VI.2  Glossary

A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z

- A -

Advanced Technology Attachment - a disk drive interface standard based on the IBM PC ISA 16-bit bus but also used on other personal computers. The ATA specification deals with the power and data signal interfaces between the motherboard and the integrated disk controller and drive. The ATA "bus" only supports two devices - master and slave.
Advanced Technology Attachment Interface with Extensions - a standard which extends the Advanced Technology Attachment interface while maintaining compatibility with current IBM PC BIOS designs. ATA-2 provides for faster data rates, 32-bit transactions and (in some drives) DMA. Optional support for power saving modes and removable devices is also in the standard.

- B -

BIOS boot sequence
An entry in most moder BIOSes. Specifies where the BIOS should look first for an operating system. Enables to select devices in various order. Commonly available options are: 'A, C', 'C only', 'C, A', 'D, A', 'CD-ROM, C, A', 'SCSI, C ,A' or 'LAN, C, A'.

- C -

The set of tracks on a multi-headed disk that may be accessed without head movement. That is, where multiple discs are mounted on the same axle, the collection of disk tracks which are at the same distance from the spindle about which the disks rotate. Each such group forms the shape of a cylinder. Placing data that are likely to be accessed together in cylinders reduces the access significantly as head movement (seeking) is slow compared to disk rotation and switching between heads.

- E -

Extended Integrated Drive Electronics - ATA-2.

extended partition
A partition of a hard disk drive divided into smaller logical sections - logical volumes. Developed to break the limit of 4 partitions per a hard disk drive, related to small size of MBR.

- F -

FAT, FAT-16, FAT-32
File Allocation Table. File systems based on the idea of File Allocation Table. Older FAT-16 are used by all MS operating systems, newer FAT-32 is used since MS Windows 95 OSR2 was released. FAT-32 is recognized by Windows 98 and W2K, while NT 4.0 needs additional software to use FAT-32.

file system
1. A method of arrangement of directories and files, connected with an operating system which implements it.
2. A collection of directories and files.

- H -

An electronic device that reads/writes data from/to a disk. It is an interface between the magnetic physical media on which the data is stored and the electronic components that make up the rest of the hard disk. A head converts bits to magnetic pulses and stores them on a platter, and then reverses the process when the data is read back.
File system used in OS/2.

- I -

Intel Architecture - IBM PC compatible architecture or machine.
Integrated Drive Electronics - ATA.

- L -

Logical Block Addressing - A translation method used by BIOS of IBM PC compatibles to change the size limit of a hard disk drive from around 528MB to 8.4GB. The number of cylinders of a hard disk drive is decreased while the number of heads is proportionally increased, so that both parameters stay below their limits. The limits are 1024 for cylinders, 256 for heads and 64 for sector per track.

logical volume
A section of an extended partition that contains a file system.

- M -

Master Boot Record - The first sector of a hard disk drive. It stores information about partitions on that disk, the partition id, activity flag, starting cylinder/head/sector, and ending cylinder/head/sector. Four partitions are allowed.

- N -

NT Disk Signature
An entry in the MBR where Windows NT and W2K stores information on volume letter assignment. It occupies 4 bytes starting at 0x1B8 byte.
Windows NT family, including Windows 2000, file system. It provides file permisions, long filenames (case is ignored).

- O -

operating system
(OS) A low-level software interface between hardware and applications. Sometimes comes with GUI - Graphic User Interface, and additional software.

- P -

On IA machines, logical section of a hard disk drive. On UNIX systems sometimes called slice. Generally, two types of partitions are distinguished: primary and extended.
primary partition
Usually boot-able partition of a hard disk drive that contains an operating system.

- S -

Small Computer System Interface - A processor-independent standard for system-level interfacing between a computer and intelligent devices including hard disks, floppy disks, CD-ROM, printers, scanners and many more.

1. Physically, a continuous range of rotational angle of a disk, a segment of a track. Usually, physical sectors are staggered in order to give enough time to deal with one sector before the next is accessible.
2. Logically, a smallest portion of information that can be read/write at the time from/to disk, typically 512 bytes. On Macintosh and UNIX drives, sectors usually are grouped into blocks that function as the smallest data unit permitted. The terms block and sector are sometimes used interchangeably.
On x86 machines, a logical section of a partition, common for Unix operating systems. Sometimes identified with partition on these systems. Usually contains a file system, e.g. /, /var, /usr or /export.

- T -

A concentric ring on a disk surface where data is stored.

- U -

Unix File System.

- V -

Volume Boot Sector (Partition Boot Sector aka PBR) - The first sector of a partition. If the partition is boot-able, it stores an executable program to load an operating system.
Volume Table Of Contents - A table containing information on slices within a Solaris partition. The definition of a slice consists of 5 fields: slice number, tag, flag, starting sector and size. There is room for 16 slices per partition. VTOC occupies the second and third sector of the Solaris partition.
A primary partition or a logical volume.