DOS Navigator (DN) is an orthodox file manager for DOS, OS/2, and Windows. Influence DOS Navigator is an influential early implementation of orthodox file manager (OFM). By implementing three additional types of virtual file systems (VFS): XTree, Briefcase and list-based, DN launched a new generation of OFMs. It offers unlimited panels and many new important features, making it one of the most powerful (and complex) OFMs. History The initial version of DN I (v 0.90) was released in 1991, and written by Stefan Tanurkov, Andrew Zabolotny and Sergey Melnik (all from Chișinău, Moldova). After that, DN was rewritten using Turbo Vision by Stefan Tanurkov and Dmitry Dotsenko (Dotsenko developed DN at Moscow State University). These versions are sometimes referred as DN II. In 1993, Slava Filimonov invited Stefan to join him to continue producing and publishing DN with joint efforts. Slava programmed new components, design and made countless optimizations and improvements. He wrote a new software key protection system that remained unbroken for almost four years after its introduction. DN II was actively developed until the start of 1995, until version 1.35. Several other programmers participated in development after version 1.35. Starting from version 1.37, Filimonov and Ilya Bagdasarov were in charge of bug-fixing. Filimonov and Bagdasarov solely maintained, developed and released versions 1.37 through 1.39. After they left, DN was maintained again by Tanurkov and Maxim Masiutin. In 1998, the development mostly took a bug-fixing direction as Ritlabs' product The Bat! became a more promising software product with much better commercial potential. The last shareware version was 1.50. In late 1999, Ritlabs decided to make version 1.51 of the DOS Navigator completely free with freely available source code. Several open source DN branches currently exist including win32/dpmi/os2 version "dn/2" and Linux port attempt "dn2l". Disadvantages The original DN contains a large amount of assembler code, complicating ports to other platforms. The cross-platform version, DN OSP, in turn, is tied to the Virtual Pascal compiler and runtime library, which are no longer supported. No version of DN as of January 2022 supports Unicode on platforms other than Windows, although cross-platform implementation of Turbo Vision for Pascal with Unicode support exists. The source code license is compromised. Source code license DN source code was published under the 3-clause BSD license. However, the code included an implementation of the Turbo Vision library based on the version from the Turbo Pascal distribution, and