The Atmel AT89C4051 is a 20 Pin, high-performance CMOS 8-bit microcontroller with
4K bytes of Flash memory. This is compatible MCS-51 instruction set. The AT89C4051 provides the following standard features: 4K bytes of Flash,
128 bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five-vector, two-level interrupt
architecture, a full duplex serial port, a precision analog comparator, on-chip
oscillator and clock circuitry.