HP21 scientific RPN calculator
Beauty of RPN with one of the first Hewlett-Packard calculators - HP 21.
What's HP21 scientific RPN calculator APK?
HP21 scientific RPN calculator is a app for Android, It's developed by Milan Cisár author.
First released on google play in 9 years ago and latest version released in 6 years ago.
This app has 10 download times on Google play and rated as 4.50 stars with 152 rated times.
This product is an app in Tools category
The HP-21 was a scientific calculator produced by Hewlett-Packard between 1975 and 1978. It was designed as a replacement for the HP-35, and was the first from so called Second Generation Handheld Calculators.
As with most HP calculators then and now, the HP-21 used RPN entry logic, with a four-level stack. It also had a single user-accessible memory register. A shift key provided access to functions whose legends were printed on the fronts of the tall trapezoidal keys.
To enhance practical usability, display was modified to show both X and Y register. Also I have eliminated mechanical DEG/RAD switch and moved the function under DSP button.
HP21 has few big enough buttons to be used comfortably on mobile devices.
As with most HP calculators then and now, the HP-21 used RPN entry logic, with a four-level stack. It also had a single user-accessible memory register. A shift key provided access to functions whose legends were printed on the fronts of the tall trapezoidal keys.
To enhance practical usability, display was modified to show both X and Y register. Also I have eliminated mechanical DEG/RAD switch and moved the function under DSP button.
HP21 has few big enough buttons to be used comfortably on mobile devices.