Fenestra '98

Fenestra '98 was a computer operating system developed by Macrosoft and was used by certain terminals aboard the Control station ENCLAVE. The DataPlex 2000 SmarTerminal that it was operating from was covered in a thick layer of dust for some reason.

Appearances
Fenestra '98 is mentioned only in Fallout 2.

Behind the scenes
Fenestra means "window" in Latin, making it a cultural reference to Microsoft Windows, in particular, Windows 98.