The Tape Operating System (TOS) was an IBM operating system for the System 360, used in the early days around 1965 to support the IBM 360 model 30 et al. TOS was a predecessor to IBM's Disk Operating System.
TOS died out really early as disks such as the IBM 2311 and IBM 2314 became common with the IBM 360 whereas they had been a real luxury on the IBM 7090.
