TempleOS

TempleOS is a biblical-themed lightweight operating system created in the span of a decade by the American programmer Terry A. Davis. The software is a x86-64 bit, multi-tasking, multi-cored, public domain, open source, ring-0-only, single address space, non-networked, PC operating system for recreational programming. The operating system was designed to be the Third Temple according to Davis and uses an interface similar to a mixture of DOS and Turbo C. Davis describes the operating system as a modern x86-64 Commodore 64 with a variation of C in place of BASIC.