Method and apparatus are disclosed for dispersing the electromagnetic energy radiated from a digital system to minimize the EMI snd RFI emanating from such a system. To accomplish this, one approach of the present invention includes a VCO which is modulated by a band-limited signal to provide a system clock signal which has a broader spectral signature than the traditional precise crystal controlled oscillator traditionally utilized in digital systems. In addition, an optional feedback stage is disclosed for compensating for frequency drift of the VCO with time. This includes a precision crystal controlled oscillator operating at substantially the same frequency as the unmodulated VCO.; This signal is then continuously compared with the modulated output signal of the VCO to generate a compensation signal which in turn is combined with the modulation signal to minimize the long-term errors and thus minimize the long-term drift of the modulated clock signal. Another approach disclosed is to modulate the amplitude of the bus voltage being provided for the digital system.