
1) Technological change
Found on
https://www.crosswordclues.com/clue/legacy-system

In computing a legacy system is an old method, technology, computer system, or application program,`of, relating to, or being a previous or outdated computer system.` A more recent definition says that `a legacy system is any corporate computer system that isn`t Internet-dependent.` The term `legacy` may also have little to do with the size...
Found on
http://en.wikipedia.org/wiki/Legacy_system

An IT system that is based on out of date technologies but is still in use today. A reason for this might be because it works but nobody knows how or why and so cannot replicate it using more up to date technologies.
Found on
http://www.ft.com/dbglossary
No exact match found.