Last week NASA published a catalog of software code its developed over the years which you can now access for free. While NASA has a history of making technology it develops available to the public, other developers of proprietary software will sometimes also lift the veil on their code. Often, it's years after the software's prime and is usually shared for historical purposes. Occasionally, though, developers will make formerly proprietary code open source to encourage others to continue its development. Here are 13 pieces of classic proprietary software for which the source code is now available, either through being open sourced by its developer or, sometimes, because it was literally rescued from the trash heap by a fan.
This slideshow originally appeared on ITworld.com.