NES Calculator

This is a scientific calculator for NES, based on  http://www.crbond.com/calc65.htmand inspired by this tweet.

Controls:

• D-Pad: move the cursor
• A: press the currently selected button
• B: toggles between exp and log functions, between square and square root functions, and between normal, inverse, hyperbolic and inverse hyperbolic trigonometric functions.

Notes:

• The input is always in scientific notation. The last 3 digits on display are the current exponent. Therefore, if you type 413 it will be displayed as "4.1300000 002" (meaning 4.13 x 10²)
• The mantissa has 10 digits of precision. The last 2 digits aren't shown but they can still be inserted.

Source:

The source is available at https://github.com/wendelscardua/nes-calculator

Why?

Why not?