I am confused at a mistake I currently have in my setup. I am using this Holtek keyboard controller. Note how the letter Q is produced by connection between R0 and C1 (page 19). According to the datasheet, R0 is pin 6 input, and C1 is pin 20, output.
Now, I have a matrix where the Q button is connected to the above R0 and C1, however there's also a 1n4148 diode in series with the button that is oriented from R0 to C1. I would expect this not to work, because C1 is an output pin during the matrix scan, and R1 is an input pin. The diode is reversed with respect to the flow of current (from C1 to R0). Strangely enough, it does work, and this really is the core of the question.
Is there something in the datasheet I am misunderstanding?