FlexOS is a discontinued modular real-time multiuser multitasking operating system (RTOS) designed for computer-integrated manufacturing, laboratory, retail and financial markets. Developed by Digital Research's Flexible Automation Business Unit in Monterey, California, in 1985, the system was considered to become a successor of Digital Research's earlier Concurrent DOS, but with a new, modular, and considerably different system architecture and portability across several processor families. Still named Concurrent DOS 68K and Concurrent DOS 286, it was renamed into FlexOS on 1 October 1986 to better differentiate the target audiences. FlexOS was licensed by several OEMs who selected it as the basis for their own operating systems like 4680 OS, 4690 OS, S5-DOS/MT and others. Unrelated to Fl