The HD66420 drives and controls a dot matrix graphic LCD(Liquid Crystal Display) using a bit-mapped method. It provides a highly flexible display through its on-chip display RAM, in which each two bits of data can be used to turn on or off one dot on LCD panel with four-level grey scale. A single HD66420 can display a maximum of 160x80 dots using its powerful display control functions. It can display only eight lines out of eighty lines. This function realize low power consumption because high voltage for driving LCD is not needed. An MPU can access HD66420 at any time, because the MPU operations are asynchronous with the HD66420's system clock and display operation. Its low-voltage operation at 2.2 to 5.5V and standby function provides low power dissipation, making the HD66420 suitable for small portable device applications.