Ada is a systems language, too. It was used in many OS's. Several are below: Army Secure OS (A1-class design) http://www.dtic.mil/dtic/tr/fulltext/u2/a340370.

Ada is a systems language, too. It was used in many OS's. Several are below: Army Secure OS (A1-class design) http://www.dtic.mil/dtic/tr/fulltext/u2/a340370.pdf http://www.dtic.mil/dtic/tr/fulltext/u2/a340370.pdf Fault-Tolerant, Parallel, Mainfraim-style OS/Platform https://en.m.wikipedia.org/wiki/BiiN https://en.m.wikipedia.org/wiki/BiiN MarteOS Real-Time OS https://marte.unican.es https://marte.unican.es Muen Separation Kernel https://muen.codelabs.ch https://muen.codelabs.ch