psx controller problem

Owen

I'm using a psx2 controller connected to my propellar chip amd have a problem with the output of the device. the psx outputs one byte for each axis of the joystick so joystick foward is 255 joystick down is 0 joystick centered is 127. the problem is that the joystick physically has a circle shaped opening at the joystick instead of a square preventing the joystick from a full diagonal position. it is not possible for both x and y to be 255 , does anyone know what the purpose of this is? or is there a way around it with software? whouldn't the playstation want the full byte of information? thanks in advance

Owen