Does this sound like the situation facing your IT department?
… It probably supports an installed set of information systems that are used by the business to control and report on its operations. There is always more than just one system, and possibly hundreds, many doing the same work as many others. Some may be decades-old, a few may be recent and using fairly new technologies, with the implementations of the rest spread-out over the history of the department since that first ‘computing machine’ was purchased, with the wide range of development and operating technologies which that implies. The still favourite term for describing this