This is sad. The 4000-series computers were very interesting machine that used essentially the guts of a Wang 300-series electronic calculator for the arithmetic unit, So the machine had built in logarithmic functions that were implemented in "hardware", and did math in decimal. Unfortunately, it appears that no printed documentation was included in Dr. Wang's museum, and so far, no docs have appeared for the 400-series - but I keep searching. Of course, should I ever find it, it'll go straight to Al for scanning and posting on Bitsavers. More can be read at http://oldcalculatormuseum.com/d-wangcustom.html Rick Bensene The Old Calculator Museum http://oldcalculatormuseum.com