From: Christoph
Email: ballhause@gmx.de
What I've found out so far: Obviously the 801D is very similar to the 0081... Take a look at the circuit boards: The 0081: http://www.vintagecalculators.com/assets/images/SanyoICC0081_4.jpg The 801D: http://christoph.witchcraft-castle.net/gallery/Old%20Calculators/Sanyo%20ICC-801D/within.jpg My guess is the little difference in the display driver section top left comes from the different display tubes. The 0081 has 7-segment tubes while the 801D has Nixie tubes... The chips are exactly the same. The 8001 and 8004 in my 801D are dated to 20th week of 1971 whereas the 8002 and the 8003 are dated to 23th week...
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