A keyboard input device.

Users can interact with programs through a hexadecimal keypad that was present in the original Chip-8 computer.

Keys are represented by hexadecimal integers. When a user presses the F key, the key needs to be registered as 15 instead. For this purpose, you can either use the hexadecimal notation (e.g. 0xF returns 15) for a hard-coded mapping or String.to_integer/2 (e.g. String.to_integer("F", 16) returns 15) for a more dynamic approach.