The W27C520 is a high speed, low power Electrically Erasable and Programmable Read Only Memory organized as 65,536 x 8 bits. It includes latches for the lower 8 address lines to multiplex with the 8 data lines. To cooperate with the MCU, this device could save the external TTL component, also cost and space. It requires only one supply in the range of 3.0V to 3.6V or 4.5V to 5.5V in normal read mode. The W27C520 provides an electrical chip erase function. It will be a great convenient when you need to change/update the contents in the device.