EXEC 8 (sometimes referred to as EXEC VIII) was UNIVAC's operating system developed for the UNIVAC 1108 in 1964. It combined the best features of the earlier operating systems: EXEC I and EXEC II (used on the UNIVAC 1107). EXEC 8 was one of the first commercially successful multiprocessing operating systems. It supported simultaneous mixed workloads comprising batch, time-sharing and real-time. It supported one file system with a flat naming structure across many drums and/or spindles. It supported a well-received transaction processing system. Unisys continues to market and support systems founded on the original 1108 and EXEC 8 designs.