Microchip Technology, Inc. AT89S4051

Low-power, high-performance CMOS 8-bit microcontroller with 4KB ISP flash memory. The device uses Microchip high-density nonvolatile memory technology and is compatible with the industry-standard MCS??-51 instruction set. An enhanced CPU core can fetch a single byte from memory every clock cycle and is capable of 20-MIPS throughput. The new CPU core runs at a much lower speed, greatly reducing power consumption.