Modern Operating System --- Graphical User Interface

Most personal computers offer a GUI (Graphical User Interface). The acronym GUI is pronounced ''gooey''.

The GUI was invented by Douglas Engelbart and his research group at the Stanford Research Institute.

It was then copied by researchers at Xerox PARC. One fine day, Steve Jobs, cofounder of Apple, was touring

PARC and saw a GUI on a Xerox computer and said something to the effect of "Holy mackerel, this is the

future of computing". The GUI gave him the idea for a new computer, which became the Apple Lisa. The

Lisa was too expensive  and was a commercial failure, but its successor the Macintosh, was a huge success.

A GUI has four essential elements, denoted by the characters WIMP. These letters stand for Windows, Icons,

Menus, and Pointing Device, respectively. Windows are rectangular blocks of screen area used to run programs.

Icons are little symbols that can be clicked on to cause some action to happen. Menus are lists of actions from

which one can be chosen. Finally, a pointing device is a mouse, trackball, or other hardware device used to

move a cursor around the screen to select items. The GUI software can be implemented in either user-level

code, as is done in UNIX systems, or in the operating system itself, as in the case in Windows.