Using 8255 port to form matrix keyboard circuit

Shown is a 4X8 matrix keyboard configured with 8255j port . At dawn, the PA port of 8255 is initialized to the output working mode and
used as a column line. The PC port is initialized to the input working mode and used as a row line. Connect a button at the intersection of each row line and column line,
and then give each Set a number [key value] for each button. You can define some keys as function keys and other keys as numeric keys as
    needed
.