Abstract: A computer based trainer employing a microprocessor connected to a program memory and input and output devices by means of common address and data buses. The input devices include a plurality of student operable switches, associated with a pictorial presentation of the lesson subject, which are interconnected in a switch matrix whereby the state of the individual switches may be sensed by energizing columns and sensing rows of the matrix under control of a stored program. The teaching machine also utilizes a non-volatile memory in which at least a portion of the program is stored.