User interface. Almost all operating systems have a
This interface can take several forms. One is a Dcfr'":c;~,
which uses text commands and a method for entering them
(say, a program to allow entering and editing of commands). Another is
a batch in which commands and directives to control those
commands are entered into files, and those files are executed. Most
commonly, a is used. Here, the interface
is a window system with a pointing device to direct I/0, choose from
menus, and make selections and a keyboard to enter text. Some systems