Apparatus utilizing electrical activity of the brain to control a series of low-stimuli educational exercises (displayed on a computer monitor to increase the following educational components: time on-task, visual tracking, short-term memory, visual discriminatory processing, auditory discriminatory processing, and focus. In order to erase the NROM cell, a constant voltage is coupled to the gate input. In an electrical line width measurement, the reduced width of the structure is measured and compared either with the original width or with that width of a further partial element produced by the overforming. The constraining condition information is set so that the phase of a next dot pattern to be generated has an opposite phase relationship in a low frequency region with respect, to the already printed dot pattern.