amen zwa, esq.<p>In my career as an <a href="https://mathstodon.xyz/tags/ElectricalEngineer" class="mention hashtag" rel="tag">#<span>ElectricalEngineer</span></a> <a href="https://mathstodon.xyz/tags/EE" class="mention hashtag" rel="tag">#<span>EE</span></a> over the past four decades, I've used several <a href="https://mathstodon.xyz/tags/HP" class="mention hashtag" rel="tag">#<span>HP</span></a> <a href="https://mathstodon.xyz/tags/RPN" class="mention hashtag" rel="tag">#<span>RPN</span></a> <a href="https://mathstodon.xyz/tags/calculators" class="mention hashtag" rel="tag">#<span>calculators</span></a> (yes, only RPN). Of all those, my absolute favourites, in descending preference, are these:</p><p>• HP-15C<br />• HP-41CX<br />• HP-32S<br />• HP-35s</p>