Eumel

L2 (also known as EUMEL " Extendable multiuser Microprocessor ELAN System") is a 16 -bit operating system that was developed in 1979 by a team led by Jochen Liedtke at the University of Bielefeld.

Originally written for the Z80 processor, it was later ported to Intel architectures. In addition, there were ports for the Z8000 ( Olivetti M20), the Atari 520ST and the Commodore Amiga. Main concepts of L2 is its persistence and the micro- kernel architecture. Successor of L2 L3 and L4.

Orthogonal persistence means that a failure of the power supply only lost a few minutes and the system automatically starts work again at the last checkpoint. This highly effective protection mechanism was incorporated into the operating system L3 ( 32- bit), which is, inter alia, at TÜV Süd in use.