Abandonware is a product, typically software, ignored by its owner and manufacturer, and for which no official support is available.
Within an intellectual rights contextual background, abandonware is a software (or hardware) sub-case of the general concept of orphan works. Museums and various organizations dedicated to preserving this software continue to provide legal access.
The term "abandonware" is broad, and encompasses many types of old software. Definitions of "abandoned" vary, but in general it is like any item that is abandoned – it is ignored by the owner, and as such product support and possibly copyright enforcement are also "abandoned".
Types.
Commercial software unsupported but still owned by a viable company
The availability of the software depends on the company's attitude toward the software. In many cases, the company which owns the software rights may not be that which originated it, or may not recognize their ownership. Some companies, such as Borland, make some software available online, in a form of freeware. Others, such as Microsoft, do not make old versions available for free use and do not permit people to copy the software.
Commercial software owned by a company no longer in business.
When no owning entity of a software exists, all activities (support, distribution, IP activities, etcetera) in relation to this software have ceased. If the rights to a software are non-recoverable in legal limbo ("orphaned work"), the software's rights cannot be bought by another company, and there is no company to enforce the copyright. An example of this is Digital Research's original PLI compiler for DOS: which was considered for many years as without an owner; Micro Focus, which acquired Novell, which had bought Digital Research's assets, owns this old PLI compiler, but has a more up-to-date PLI offering.
Shareware whose author still makes it available.
Finding historical versions, however, can be difficult since most shareware archives remove past versions with the release of new versions. Authors may or may not make older releases available. Some websites collect and offer for download old versions of shareware, freeware, and (in some cases) commercial applications. In some cases these sites had to remove past versions of software, particularly if the company producing that software still maintains it, or if later software releases introduce digital rights management, whereby old versions could be viewed as DRM circumvention.
Unsupported or unmaintained shareware.
Open source and freeware programs that have been abandoned.
In some cases, source code remains available, which can prove a historical artifact. One such case is PC-LISP, still found online, which implements the Franz Lisp dialect. The DOS-based PC-LISP still runs well within emulators and on Microsoft Windows.
Orphaned code.
The source code or executable might still be available but the author is unknown or only identified by a dead email or equivalent and there is no realistic prospect of finding the owner of the IP.
