Cairo (operating system)

Cairo was the codename of an unreleased software project by Microsoft, intended to bring next-generation technologies to Windows NT. The project was originally announced at the 1991 PDC (Professional Developers Conference) and later demoed at the 1993 PDC.

SKUs

Three different retail SKUs were planned for Microsoft Cairo, all aimed at the enterprise market:

Cairo Advanced Desktop would include the core OS, new user interface, and networked storage/printer sharing. It was designed as the client for Cairo Servers.
Cairo Advanced Server would be a superset of Advanced Desktop that would additionally include all the server roles, as well as domain services, networked messaging, and management tools.
Cairo Design Environment would be intended for developers to build Cairo-friendly applications, including a Smart Folders SDK, authoring tools, design tools, debugger, documentation, and Visual Basic for Applications.

Windows NT 3.1

DCE RPC implementation (Remote Procedure Call, allows inter-machine or inter-process procedure calls, for example, to use with distributed computing)
COM (Component Object Model, a standardized communication model meant to be used with RPC)
OLE (Object Linking and Embedding, allowing files from one app to be embeddable and editable in other OLE-compliant apps)

Windows NT 3.5x / 4.0

Cairo OFS (Object File System, a relational filesystem meant to replace NTFS)
Cairo OFS Indexing (metadata system for OFS, later turned into Content Indexing and Windows Desktop Search)
Cairo Domains (based on x.500 Directory Services, later turned into Active Directory for Windows 2000)

Windows 95 / NT 4.0 / other

Cairo User Interface (later turned into the Windows 95/NT 4.0 Shell)
Cairo Messaging (based on x.400 Messaging Services, later turned into Microsoft Exchange)
Cairo Smart Folders (would later influence Windows 7 libraries)

List of known builds

Build list legend

# Available build

i Confirmed build

? Unconfirmed build

x Fake build

References

https://web.archive.org/web/20070513113123/http://www.windowsitpro.com:80/Articles/Index.cfm?ArticleID=48&DisplayTab=Article
https://web.archive.org/web/20070301102726/https://sigchi.org/chi96/proceedings/desbrief/Sullivan/kds_txt.htm