TempleOS (formerly J Operating System, SparrowOS and LoseThos) is a biblical-themed lightweight operating system designed to be the Third Temple prophesied in the Bible. It was created by American programmer Terry A. Davis, who developed it alone over the course of a decade after a series of episodes that he later described as a revelation from God. The OS was released in 2013 and last updated in 2017.
TempleOS was characterized by Davis as a modern x86-64 Commodore 64. He proclaimed that he was in direct communication with God, and that God ordered the OS to have a 640×480 resolution, 16 color display, and a single audio voice. It was programmed with an original variation of C (named HolyC) in place of BASIC and uses an interface similar to a mixture of DOS and Turbo C. It also included an original flight simulator, compiler, and kernel.
Davis struggled with schizophrenia and periods of homelessness throughout his adult life. Over the years, he posted hours of video blogs to social media, and by the time of his death, had amassed a small online following. One fan described him as a “programming legend”, while another, a computer engineer, compared the development of TempleOS to a one-man-built skyscraper. Davis died in a train accident on August 11, 2018 at the age of 48.