Minix-vmd
Minix-vmd is a free and open source operating system which was created from Minix, and added some additional features such as virtual memory and X Window System support.
Minix-vmd only ran on IA-32 and compatible microprocessor architectures. It was written by many of the same authors who develop Minix, at the Vrije Universiteit (VU) in Amsterdam. The acronym reputedly stands for "VU Minix Distribution".
The operating system, according to its authors, was not meant to be a general purpose use OS and was created to meet specific needs they had rather than to be a general use OS like Linux. It also does not share the educational goals of Minix.
Nevertheless, the OS may have been of interest to others for various purposes, due to its small resource usage compared with other operating systems and other factors. However, Minix 3 added Minix-vmd's functions into Minix itself.