The DAC-1 traces lines drawn on a computer screen. It is described as being “similar to drawing lines with a pencil on the CRT [television] screen”. However, the optical pen is not used directly on the screen but on a conductive surface placed on the monitor and is closer to drawing with a pen or pencil than using an optical pen. Jordan Kauffman also points out that “DAC-1 will, however, prove impractical in use. The effort of stretching the arm for long periods of time is too much for designers (...) to use effectively.”