Disk Masher System

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The Disk Masher System (.dms) is an often used method on the Amiga, to create a compressed image of a disk (usually floppy). The disk is read block-by-block, and thus its data structure is maintained. DMS won approval particularly in the demo scene and the Warez scene, since with this tool, disk images could generally be transferred easily with telecommunication modems to mailbox networks like FidoNet for efficient distribution. [1]

Amiga family of personal computers sold by Commodore

The Amiga is a family of personal computers introduced by Commodore in 1985. The original model was part of a wave of 16- and 32-bit computers that featured 256 KB or more of RAM, mouse-based GUIs, and significantly improved graphics and audio over 8-bit systems. This wave included the Atari ST—released the same year—Apple's Macintosh, and later the Apple IIGS. Based on the Motorola 68000 microprocessor, the Amiga differed from its contemporaries through the inclusion of custom hardware to accelerate graphics and sound, including sprites and a blitter, and a pre-emptive multitasking operating system called AmigaOS.

In signal processing, data compression, source coding, or bit-rate reduction involves encoding information using fewer bits than the original representation. Compression can be either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information.

Floppy disk disk storage medium

A floppy disk, also known as a floppy, diskette, or simply disk, is a type of disk storage composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic enclosure lined with fabric that removes dust particles. Floppy disks are read and written by a floppy disk drive (FDD).

The DiskMasher format is copyright-protected and has problems storing particular bit sequences due to bugs in the compression algorithm, but was widely used in the pirate and demo scenes. To avoid these issues, a number of other disk compressors were developed that used alternative disk reading and compression methods, for instance, xDM [2] or XAD (software).

XAD (software)

The XAD system is an open-source client-based unarchiving system for the Amiga. This means there is a master library called xadmaster.library which provides an interface between the client and the user application and there are clients handling the special archive formats. Three different types to handle file and disk archives and also disk image files (filesystem) are possible. They can be made by anyone. The master library itself includes some of these clients internally to make the work somewhat easier for the package maintainer and the user installing it.

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The Amiga Fast File System is a file system used on the Amiga personal computer. The previous Amiga filesystem was never given a specific name and known originally simply as "DOS" or AmigaDOS. Upon the release of FFS, the original filesystem became known as Amiga Old File System (OFS). OFS, which was primarily designed for use with floppy disks, had been proving slow to keep up with hard drives of the era. FFS was designed as a full replacement for the original Amiga filesystem. FFS differs from its predecessor mainly in the removal of redundant information. Data blocks contain nothing but data, allowing the filesystem to manage the transfer of large chunks of data directly from the host adapter to the final destination.

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Executable compression is any means of compressing an executable file and combining the compressed data with decompression code into a single executable. When this compressed executable is executed, the decompression code recreates the original code from the compressed code before executing it. In most cases this happens transparently so the compressed executable can be used in exactly the same way as the original. Executable compressors are often referred to as "runtime packers", "software packers", "software protectors".

<i>The Colony</i> (video game) video game

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Amiga Disk File (ADF) is a file format used by Amiga computers and emulators to store images of disks. It has been around almost as long as the Amiga itself, although it was not initially called by any particular name. Before it was known as ADF, it was used in commercial game production, backup and disk virtualization. ADF is a track-by-track dump of the disk data as read by the Amiga operating system, and so the "format" is really fixed-width AmigaDOS data tracks appended one after another and held in a file. This file would, typically, be formatted, like the disk, in OFS.

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AmigaOS is a family of proprietary native operating systems of the Amiga and AmigaOne personal computers. It was developed first by Commodore International and introduced with the launch of the first Amiga, the Amiga 1000, in 1985. Early versions of AmigaOS required the Motorola 68000 series of 16-bit and 32-bit microprocessors. Later versions were developed by Haage & Partner and then Hyperion Entertainment. A PowerPC microprocessor is required for the most recent release, AmigaOS 4.

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Floppy disk variants

The floppy disk is a data storage and transfer device which was ubiquitous from the mid-1970s well into the 2000s. Besides the 3½-inch and 5¼-inch formats used in IBM PC compatible systems, or the 8-inch format that preceded them, many proprietary floppy disk formats were developed, either using a different disk design or special layout and encoding methods for the data held on the disk.

References

  1. "xDMS - Amiga DMS archive extractor".
  2. "xDM - Amiga DMS alternative".

xDMS - Tool for AmigaOS, MS-DOS and Linux for decompressing DMS files.