This calculator application should be considered experimental and its results should not be used for anything important. In particular, there are situations where the numeric display is known to be totally wrong. This JavaScript simulator is a very faithful simulation with the exception of some rounding errors. Both the HP-35 and the JavaScript produce rounding errors, but they do so in different situations.

All credits to http://neil.fraser.name
You may want to download your own copy. The ZIP file has all the code and graphics (50KB).