How does the 4x4 Matrix Key Board on the microcontroller work

Hello,

in school we are programming a microcontroller. We have now a homework, that we have to learn how to controll the 4x4 Matrix Keyboard on the Microcontroller.

Here how it looks like:

              P6.4    P6.5     P6.6     P6.7

 P8.3       A1      A2        A3       A4

 P8.2       B1      B2        B3       B4

 P8.1       C1      C2        C3       C4

 P8.0       D1      D2        D3       D4

For example if A1 is pressed P8.3 = 0 and P6.4 = 0.

I try it on many ways to controll it, when someone press a button, but i cant find out how it work.

I use for example this Code.

Thanks for help

if ((P6 & 0x01F)== 0x0E0 && (P8 & 0x0F8) == 0x07)
        {

          .....

        }