sent back is b 7 0 the signal called oena represents the driver chip internal control signal for bi directional sdio the mpu has its own memory where the system software and related parameters of required types of driver chips and the lcd displays to operate the lcd system are stored in an initialization step for instance during the power up sequence the mpu can read the lcd module identification register and can then assign and load the specific software and the parameters required to the lcd driver chip it is obvious that this invention applies also for the case where more than one driver chips are used in an lcd system in case all driver chips are identical it is sufficient to keep said lcd module identification register on one of the lcd driver chips used in case the lcd driver chips have different physical characteristics e g different types of lcd driver chips are driving the lcd rows and columns said lcd module identification register has to be implemented on each lcd driver chip in this case the mpu will read from each lcd driver chip said identification register and will supply the specific parameters to each of said lcd driver chips individually fig4.