You are probably thinking of EROS <https://en.wikipedia.org/wiki/EROS_(microkernel) https://en.wikipedia.org/wiki/EROS_(microkernel)> But there have been sever

You are probably thinking of EROS <https://en.wikipedia.org/wiki/EROS_(microkernel) https://en.wikipedia.org/wiki/EROS_(microkernel)> But there have been several others also based on similar ideas, such as Mungi. In recent years, there is Twizzler, intended for NVRAM. <https://www.youtube.com/watch?v=0Ix5DYKxzLI https://www.youtube.com/watch?v=0Ix5DYKxzLI>