The AT89C4051-24PU is a 8-bit low-voltage high-performance CMOS Microcontroller with 4kB of flash programmable and erasable read-only memory. The device is manufactured using Atmel's high-density non-volatile memory technology and is compatible with the industry-standard MCS-51 instruction set. By combining a versatile 8-bit CPU with flash on a monolithic chip, the Atmel AT89C4051 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The AT89C4051 provides the following standard features, 4kB 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 analogue comparator, on-chip oscillator and clock circuitry. In addition, the AT89C4051 is designed with static logic for operation down to zero frequency and supports two software-selectable power saving modes.