Open source software
Open source software software (also compared to free software) is computer software that gives users the freedom to run the software for any purpose as well as to study, modify, and distribute the original software and the adapted versions.
Free software and open source software
Although Free Software Foundation founder Richard M. Stallman disagrees with the "Open Source Software Definition" (OSI, v. 1.9) and "open source" terminology in favor of his own "Free Software Definition" (Stallman, v. 1.111) and "Free software" taxonomy (Stallman, "Why Open Source misses…"), there is no significant practical difference between them. The essence of both terms is that anyone may view and modify the program's source code, and that both the program and its source code may be shared with others. This article assumes the more general definition.
FreeDOS and open source software
We encourage programmers to release their software under an open source software license such as the GNU General Public License (GPL), which says in part from its Preamble:
The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Lesser General Public License instead.) You can apply it to your programs, too.
When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things.
Anyone may sell an operating system distributed under the GNU GPL (such as FreeDOS) so long as there is a distinction made as to what the customer is actually buying. That is, distributors may not claim that they own or wrote the program, and that they don't reserve any rights to it.
Additionally, distributors must share any changes they make under the same open source software license. For example, if someone adds native FAT32 support into the FreeDOS kernel, and shares that new kernel, then those changes also fall under the GNU GPL. However, if they add FAT32 support via an add-on TSR program and simply bundle it with the rest of FreeDOS, then the GNU GPL does not apply to that program.
The idea is to protect open source software and its authors. No one else should be able to take their code and misrepresent it, or worse, turn open source software into proprietary software.
Examples of open source software licenses
Most FreeDOS programs are distributed under the GNU General Public License (most use version 2, a few use version 3):
- GNU GPL
Many FreeDOS libraries are available under the similar GNU Lesser General Public License:
- GNU LGPL
Other FreeDOS programs are distributed under similar free software or open source software licenses:
- Apache License
- Artistic (Perl) License
- BSD License
- Express License
- MIT License
- Public Domain
- OpenWatcom License