Institutional Repositories and Discovery Layers are newer library systems
Institutional or Digital Repositories and Open-source and Commercial Discover Layers are recent additions to the library systems that started in early-to-mid 2000s.
Institutional Digital Repositories are a class of software for preserving and accessing digital content. To properly store digital objects requires that the digital repository meet two challenges; first, is the physical preservation of the digital object on either a hard-drive (even if that hard-drive is abstracted in a virtual server) or other magnetic or optical medium like digital tape or CD-ROM. The second challenge is making sure that the data is accessibility through software means. Often digital objects become unusable because of a combination of the two; i.e. the digital object can only be accessed through an obsolete software program and is located on old media like a floppy disk.
Discovery systems, both open-source (Blacklight, VuFind) or commercial products like Innovative Interfaces' Encore, Ex Libris Summon, OCLC's WorldCat Local, and Ebsco's Discovery Service. All of these systems attempt to replicate a "Google" like search with puesdo-boolean searches on indexes that include the library's catalog, digital repositories, and purchased and opens-access article index and full-text databases.