A program inputs its data from the standard input device by calling Java’s System.in.read() method. Look in the SDK documentation and you’ll discover a class called System.

The program will tell the CPU how to process the input information and what form to send the output in. For example, we might use a keyboard to send some text input into the computer.

Whenever a particular program is executed, its output gets sent to your screen’s File Descriptor. Then, you can see the program output on the display screen. If the program output gets sent to your ...