(from the LSX Unix Restoration Page)
LSX is a port of Sixth Edition Unix by Heinz Lycklama to the LSI-11, a cut-down version of the PDP-11 with a microprocessor CPU. It was feared lost as it was never released outside of Bell Labs.
As with Mini Unix, LSX retains most of the features of Sixth Edition Unix, but is scaled back. There is only one process in memory at any time, and the available memory to the process is tiny. Pipes are implemented with temporary files on disk etc.
The files here come from the LSX Unix Restoration Page, and were donated by Leonid Broukhis.