GO-21 SciRPN is a nostalgic iPhone app that faithfully emulates the HP-21 Pocket Scientific Calculator fromThis retro calculator experience offers the classic Reverse Polish Notation (RPN) method and a 10-digit LED display, mimicking the vintage device's look and feel.

With GO-21 SciRPN, users can enjoy features like four stack registers with roll down, a storage register with arithmetic memory operators, and a wide range of mathematical functions including trigonometric, logarithmic, and power functions. The app also provides additional views for stack/storage registers, a keystroke log, and the ability to copy from and paste to the calculator display, enhancing the retro calculator experience.