80C851/83C851 is a high-performance microcontroller fabricated with Philips high-density CMOS technology. It has 8-bit CPU, 4k × 8 ROM, 128 × 8 RAM, 256 × 8 EEPROM, 32 I/O pins, two 16-bit counters/timers, seven-source, five vector, two-priority level nested interrupt structure, serial I/O port, on-chip oscillator and clock circuits.