The AT89C51 Microcontroller IC is a 8-bit High-performance Microcontroller with 32kB flash. It retains all features of the 80C52 with 256 bytes of internal RAM, a 9-source 4-level interrupt controller and three timer/counters. It features a programmable counter array, an XRAM of 1024 bytes, hardware watchdog timer, keyboard interface, SPI interface, versatile serial channel that facilitates multiprocessor communication (EUART) and a speed improvement mechanism (X2 mode). We recommend implementing an external brown-out to prevent any flash/EEPROM corruption during power-on or power-off. The AT89C51 is a high-performance flash version of the 80C51 8-bit microcontrollers. It contains a 16k or 32kB flash memory block for program and data. The flash memory can be programmed either in parallel mode or in serial mode with the ISP capability or with software. The programming voltage is internally generated from the standard VCC pin.