Updates to another one of these were formerly named for types of big cats.
Andrew Tanenbaum created a "mini" one of these that was widely used as a teaching tool. The game Space Travel inspired Ken Thompson to develop one of these that make use of "pipes." Multics greatly influenced one of these for which X-11 provides a graphical user interface. Fedora and Debian are distributions of one of these that was developed by Linus Torvalds and has a penguin as a mascot. Updates to another one of these were formerly named for types of big cats. For 10 points, name this type of software exemplified by Linux and Microsoft Windows.
Andrew Tanenbaum created a "mini" one of these that was widely used as a teaching tool.
operating systems [or OS; accept Unix on an early buzz; prompt on "kernel"] 