In computing, an optical disc drive is a disc drive that uses laser light or electromagnetic waves within or near the visible light spectrum as part of the process of reading or writing data to or from optical discs. Some drives can only read from certain discs, but recent drives can both read and record, also called burners or writers. Compact discs, DVDs, and Blu-ray discs are common types of optical media which can be read and recorded by such drives.
A live CD is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading from a hard disk drive. A live CD allows users to run an operating system for any purpose without installing it or making any changes to the computer's configuration. Live CDs can run on a computer without secondary storage, such as a hard disk drive, or with a corrupted hard disk drive or file system, allowing data recovery.
An optical disc image is a disk image that contains everything that would be written to an optical disc, disk sector by disc sector, including the optical disc file system. ISO images contain the binary image of an optical media file system, including the data in its files in binary format, copied exactly as they were stored on the disc. The data inside the ISO image will be structured according to the file system that was used on the optical disc from which it was created.
Alcohol 120% is a disk image emulator and disc burning software for Microsoft Windows developed by Alcohol Soft. An edition named Alcohol 52% is also offered which lacks the burning engine. The software can create image files from a source CD/DVD/Blu-ray, as well as mount them in virtual drives, all in the proprietary Media Descriptor File format; images in this format consist of a pair of .mds and .mdf files.
A disk enclosure is a specialized casing designed to hold and power hard disk drives or solid state drives while providing a mechanism to allow them to communicate to one or more separate computers.
SafeDisc is a copy protection program for Microsoft Windows applications and games distributed on optical disc. Created by Macrovision Corporation, it was aimed to hinder unauthorized disc duplication. The program was first introduced in 1998 and was discontinued on March 31, 2009.
SecuROM is a CD/DVD copy protection and digital rights management (DRM) system developed by Sony DADC and introduced in 1998. It aims to prevent unauthorised copying and reverse engineering of software, primarily commercial computer games running on Windows. The method of disc protection in later versions is data position measurement, which may be used in conjunction with online activation DRM. SecuROM gained prominence in the late 2000s but generated controversy because of its requirement for frequent online authentication and strict key activation limits. A 2008 class-action lawsuit was filed against Electronic Arts for its use of SecuROM in the video game Spore. Opponents, including the Electronic Frontier Foundation, believe that fair-use rights are restricted by DRM applications such as SecuROM.
A cue sheet, or cue file, is a metadata file which describes how the tracks of a CD or DVD are laid out. Cue sheets are stored as plain text files and commonly have a .cue filename extension. CDRWIN first introduced cue sheets, which are now supported by many optical disc authoring applications and media players.
A CloneCD Control File is a text descriptor with the extension .ccd used by CloneCD to store the subcode data of a CD/DVD image. These files need to be combined with an image file to be burned. It may also come with a subchannel file.
ImgBurn is an optical disc authoring program that allows the recording of many types of CD, DVD and Blu-ray images to recordable media. Starting with version 2.0.0.0, ImgBurn can also burn files and data directly to CD or DVD. It is written in C++. It supports padding DVD-Video files so the layer break occurs on a proper cell boundary.
AVCHD is a file-based format for the digital recording and playback of high-definition video. It is H.264 and Dolby AC-3 packaged into the MPEG transport stream, with a set of constraints designed around the camcorders.
CDemu is a free and open-source virtual drive software, designed to emulate an optical drive and optical disc on the Linux operating system.
Target Disk Mode is a boot mode unique to Macintosh computers.
An NRG file is a proprietary optical disc image file format originally created by Nero AG for the Nero Burning ROM utility. It is used to store disc images. Other than Nero Burning ROM, however, a variety of software titles can use these image files. For example, Alcohol 120%, or Daemon Tools can mount NRG files onto virtual drives for reading.
The Linux booting process involves multiple stages and is in many ways similar to the BSD and other Unix-style boot processes, from which it derives. Although the Linux booting process depends very much on the computer architecture, those architectures share similar stages and software components, including system startup, bootloader execution, loading and startup of a Linux kernel image, and execution of various startup scripts and daemons. Those are grouped into 4 steps: system startup, bootloader stage, kernel stage, and init process. When a Linux system is powered up or reset, its processor will execute a specific firmware/program for system initialization, such as Power-on self-test, invoking the reset vector to start a program at a known address in flash/ROM, then load the bootloader into RAM for later execution. In personal computer (PC), not only limited to Linux-distro PC, this firmware/program is called BIOS, which is stored in the mainboard. In embedded Linux system, this firmware/program is called boot ROM. After being loaded into RAM, bootloader will execute to load the second-stage bootloader. The second-stage bootloader will load the kernel image into memory, decompress and initialize it then pass control to this kernel image. Second-stage bootloader also performs several operation on the system such as system hardware check, mounting the root device, loading the necessary kernel modules, etc. Finally, the first user-space process starts, and other high-level system initializations are performed.
Media Descriptor File (MDF) is a proprietary disc image file format developed for Alcohol 120%, an optical disc authoring program. Daemon Tools, CDemu, MagicISO, PowerDVD, and WinCDEmu can also read the MDF format. A disc image is a computer file replica of the computer files and file system of an optical disc.
MagicISO is a CD/DVD image shareware utility that can extract, edit, create, and burn disc image files. It offers the possibility of converting between ISO and CUE/BIN and their proprietary Universal Image Format disc image format.
Notable software applications that can access or manipulate disk image files are as follows, comparing their disk image handling features.
AcetoneISO is a free and open-source virtual drive software to mount and manage image files. Its goals are to be simple, intuitive and stable. Written in Qt, this software is meant for all those people looking for a "Daemon Tools for Linux". However, AcetoneISO does not emulate any copy protection while mounting.
The Advanced Disc Filing System (ADFS) is a computing file system unique to the Acorn computer range and RISC OS-based successors. Initially based on the rare Acorn Winchester Filing System, it was renamed to the Advanced Disc Filing System when support for floppy discs was added and on later 32-bit systems a variant of a PC-style floppy controller.
