The Computer Interface Base Unit with Built-In Power Supply contains 32 relays controlled by commands from the student’s computer. The computerized base unit is linked to the computer automatically by the courseware when needed, and can also be activated via a USB port by the teacher through a password-protected software. Circuit modifications (CM) and faults are switched in and out automatically by the software. A message on the student’s computer screen indicates that a CM or fault is activated. In the troubleshooting exercises, faults are also inserted automatically by the computer, thereby freeing the instructor to assist students with individual activities.