 Some more exotic operating systems ran on the 1108—one of which was RTOS, a more bare-bones system designed to take better advantage of the hardware.The affordable System 80 series of small mainframes ran the OS/3 operating system which originated on the Univac 90/30 (and later 90/25, and 90/40).The UNIVAC Series 90 first ran with Univac developed OS/9, which was later replaced by RCA's Virtual Memory Operating System (VMOS).