Hi Paul, At the end of my IC-756Pro/Pro II User Review <http://www.qsl.net/ab4oj/icom/ic756pro_notes.html> there is a paragraph entitled: The three evolutionary phases of the "DSP" HF amateur transceiver. It gives a thumbnail history of the evolution of DSP in amateur HF equipment, and may b relevant to the IC-756/756Pro discussion. Cheers for now, 73, Adam VA7OJ/AB4OJ