VRS51X580 Overview
They are pin patible and drop-in replacements for most 8051 MCUs. Ideal for a wide range of applications requiring large amounts of program/data memory, coupled with prehensive peripheral support, the VRS51x570/580 devices include 32KB/64KB of Flash memory, respectively, and 1KB of SRAM, 5 PWM output channels, a UART, three 16-bit timers, a Watch Dog timer and power down.