30-Year-Old Operating System 'PC-MOS/386' Finally Open Sourced

PC-MOS/386 "was a multi-user, computer multitasking operating system. Announced at COMDEX in November 1986," remembers Wikipedia, saying it runs many MS-DOS titles (though it's optimized for the Intel 80386 processor).

https://en.wikipedia.org/wiki/PC-MOS/386

https://virtuallyfun.com/2011/02/02/pc-mos386/