[W/K] :: disk operating system

  disk operating system
       n : an operating system that is on a disk [syn: DOS]

  disk operating system
       
           (DOS) The name of a number of operating
          systems which include facilities for storing files on disk.
          Such a system must handle physical disk I/O, the mapping of
          file names to disk addresses and protection of files from
          unauthorised access (in a multi-user system).
       
          A DOS should present a uniform interface to different storage
          device such as floppy disks, hard disks and magnetic
          tape drives.  It may also provide some kind of locking to
          prevent unintentional simultaneous access by two processes to
          the same file (or record).
       
          (1998-07-08)
       
       

  Disk Operating System
       
           (DOS) The original disk operating system
          from IBM.
       
          DOS was the low-end OS of choice on the IBM 360, the
          high-end system was called just "{OS".  DOS had a smaller
          kernel and less functionality than OS and could run on the
          typical 32K 360/30 and 64K 360/40 class machines.
       
          DOS was a successor to TOS.
       
          (1999-01-20)