Operating System

     The basic software program that organizes and services the computer and
     its peripheral devices.  The operating system supported by CA-Clipper,
     MS/PC-DOS is organized into several layers as follows:

     .  Loader is the layer which brings the operating system software
        into memory.

     .  BIOS is the basic hardware interface layer that provides
        services to the kernel and consists of initialization code and device
        drivers.

     .  Kernel is the application interface layer and provides
        services for process control, memory management, peripheral support,
        and a file system.

     .  User interface shell (COMMAND.COM) provides basic services to
        the user including an interactive mode, directory management, and a
        service for loading and executing application programs.

     .  Support programs provide extended operating services not
        resident in the user interface shell.