As its predecessor DIGI-COMP I the DIGI-COMP II is an educational computer, which actually works in a manner analogous to an electronic digital computer. It performs a surprising number (but of course not all) of the operations performed by the electronic computer, but in a visible and mechanical manner rather than electronically.

In DIGI-COMP II an electronic current impulse is simulated by a rolling ball. The ball rolls down an inclined surface under the force of gravity in an exposed manner. Thus, gravity provides the source of power for DIGI-COMP II rather than an electrical power supply. In the course of its journey the ball is directed by guides (which simulate the wires which guide electrons in the electronic computer) to the entry points of successive binary digital logic elements. The ball upon entering a logic element "questions" or "interrogates" it for its "state" and possibly changes its "state" in the process of going through it. The operation of DIGI-COMP II can be entirely automatic or manual. With appropriate settings your DIGI-COMP II can be made to:

1. Count out a specified number of balls.
2. Count in binary arithmetic.
3. Add.
4. Multiply.
5. Multiply and add.
6. Obtain either the "1's" or '2's" complement,
7. Subtract.
8. Divide.
9. Zero or clear.
10. Overflow.
11. Halt.

Moreover, all of these operations may be performed either in a "MANUAL" or an "AUTOMATIC" mode. In the AUTOMATIC mode only a single pull of the START switch is required to complete any of the operations enumerated, but in the MANUAL mode the START switch must be pulled once for each machine cycle. Thus, the MANUAL mode permits a further slowing down of the machine for demonstration purposes if desired.