The greatest HP breakthrough Scientific calcs

[zeno333]

What are the great HP scientific calculators that were state of the art when introduced...I would say the first was the HP67. A fellow student in College whose Dad was a science professor there, (His Dad bought him the calculator), had a HP67 in the Fall of 1976. The first time I saw a HP67 was his, and he wrote a moon landing program for it. Still remember that. The next milestone would be the HP41 series. Then we have the HP15, and the HP42. Then the HP48GX. And lastly, the HP Prime. Any others that should be included?