The XOR demo project that we will be using is located in a directory where the PDP++ software was installed. You should go to that directory (typically `/usr/local/pdp++') and then change to the `demo/bp' directory, which is where the project files are.
To start using the back propagation package within the PDP++ system, you
simply type bp++ to your unix command interface. After a short
time, the bp++>
prompt will appear in your command interface
window, and a small menubar window will appear somewhere on the screen.
This is the PDP++:Root
window, and it contains three menus. The
first is called Object, the second is called .projects, and the
third is called .colorspecs. The first menu's name alerts you to
the fact that this window is associated with an object, whose name
appears as the label on the window. The other menu names refer to the
children of Root, which consist of projects and colorspecs. You can
think of the '.' in front of the names as indicating that the projects
and colorspecs are children of the current object.
You are going to open a pre-defined Project and then run it. To
open the project, select .projects / Open In / Root. A
file-selector window will appear. It gives a list of directories
accessible from your current directory and files in the current
directory that might contain a project. You can either type the name of
the project file in the enter filename
box, or double click on an
item in the the list to select it. We want the project file
"xor.proj.gz". This file is saved in a compressed format, which is why
it has the ".gz" extension. Double click on it, and the project will be
loaded in (the simulator automatically uncompresses files stored in the
".gz" compression format).
After a little time for initialization, the Root menu will move to the right, and you should see two new windows on your screen: A Project window and a window called a NetView. Several other windows will be iconified, we will turn our attention to them in a moment.