question about keypad schematic given in the description of INKEY

[basiclover]

Why are there 470 ohm resistors in the rows conexions and not in the columns conexions

[Yasin]

Because in general keypads are used 4x3. It wouldn't matter if 4x4 was used. If it is used only in columns on a 4x3 keypad, there would be 3 resistors. Keypad scanning principle, columns are output, lines are read as input and then vice versa. The obtained reading is processed and the key pressed is found. These resistors are purely for precautionary purposes. In order to avoid the conflict of the output pins when more than one key is pressed accidentally or on purpose.

[basiclover]

thanks Yasin