RPN Scientific Firmware for the Spikenzielabs Calculator Kit

[Luigi Vampa]

I have found something in the code that I don't understand:

// KeyPad Layout:
//
// Columns Rows
// 3 2 1 0
//
// 7 8 9 / 0
// 4 5 6 * 1
// 1 2 3 - 2
// 0 . = + 3
//
// Value mapping for decoding
// 12 8 4 0
// 13 9 5 1
// 14 10 6 2
// 15 11 7 3
//
// ascii values returned
// 7 8 9 /
// 4 5 6 *
// 1 2 3 -
// 0 . = +
//
// shifted ascii values returned (i.e. dp key held down while other key pressed)
// A B C D
// E F G H
// I J K L
// na na na na (bottom row not used for shifted keys, since the dp key is in this row)

... so far, so good, but later we can read:

case 3:
keyvalue = 'P'; // shift '+'
break;

Does anybody know why this "case 3:" was included in the code?
I wish I could use that shift '+' to include the bigln that is left as a comment at the end of the source code.
Thanks in advance for any prospect clue.