I already have an excellent HP41C emulator on my iPhone... this is not what I am talking about.<p>It is the physical experience of holding an HP41 (or older HP2x) calculator in hands, and the feel of the keys. Nothing comes close today.<p>Also, you could hack the HP41 with what was called &quot;synthetic programming&quot; ...  Great fun.  <a href="http:&#x2F;&#x2F;www.hpmuseum.org&#x2F;prog&#x2F;synth41.htm" rel="nofollow">http:&#x2F;&#x2F;www.hpmuseum.org&#x2F;prog&#x2F;synth41.htm</a>