MODULE

       Any Verilog program begins with a keyword – called a “module.” A module is the name given to any system considering it as a black box with input and output terminals as shown in Fig.5. The terminals of the module are referred to as ‘ports’. The ports attached to a module can be of three types:

• input ports through which one gets entry into the module; they signify the input signal terminals of the module.
• output ports through which one exits the module; these signify the output signal terminals of the module.
• inout ports: These represent ports through which one gets entity into the module or exits the module; these are terminals through which signals are input to the module sometimes; at some other times signals are output from the module through these.