HP21 Emulator


I never had a HP21; but a friend did – and I sure used it a lot.

It was the first Hewlett Packard calculator I’d ever seen. It introduced me to the marvels of Reverse Polish Notation (RPN) and it is what set me on the path of owning my own HP calculators.

I’ve written an emulator for it. Note: clicking the emulator display brings up additional options.

You can: use it or install it (HTML5). You can also get a copy to keep (for free).

2 thoughts on “HP21 Emulator”

  1. Hi Sydney,

    I requested a free copy of your HP21 simulator but did not yet receive the email for downloading it. Could you please send me the email.


    1. Hi Kevin,

      Sometimes they get caught in SPAM filters. I’ve emailed it to you directly. If it hasn’t shown up in your inbox contact me via the website contact page and we’ll see what we can work out.

      All the best,


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