uLinux or picoLinux (I don't remember very well the name) -> Runs on one or two 3.5 floppies. There is a version with 3 or 4 floppies with an X-Windows included.
http://ftp.gwdg.de/linux/mulinux/ http://en.wikipedia.org/wiki/MuLinux
It was one of my first distro and it was awesome. A base system than ran in one floppy and then you could optionally add and combine more floppys depending of what you wanted (X system, IDE, games, latex, etc...) It was kind of the ancestor to Live CD
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