Directory Opus

Directory Opus (or "DOpus" as its users tend to call it) is a popular file manager program, originally written for the Amiga computer system in the early to mid-1990s. Commercial development on the version for the Amiga ceased in 1997. Directory Opus is still being actively developed and sold for the Microsoft Windows operating system by GPSoftware and there are open source releases of Directory Opus 4 and 5 for Amiga.
Directory Opus was originally developed by, and is still written by, Australian Jonathan Potter. Until 1994, it was published by well-known Amiga software company Inovatronics, when Potter joined with Greg Perry and the Australian-based GPSoftware to continue its development, and has since been published by GPSoftware.
Features.
Directory Opus has evolved since its first release in 1990 as a basic two-panel file manager. The interface has evolved significantly due to feedback given by its users. Some of the features include:
History.
Release history.
Amiga release history.
Versions 1 and 2 were only available direct from the author. Versions 3 and 4 were published by Inovatronics. Versions since 5 have been published by GPSoftware (German versions were published by Stefan Ossowskis Schatztruhe). The full version of Magellan II is included for free with AmiKit package.
Windows major release history.
All Windows versions published by GPSoftware. (German versions published by Haage & Partner Computer GmbH.)
Open source release history.
The open source 'Worker' file manager is heavily inspired by the Directory Opus 4 series.