This document describes the features and specifications of the MOSEL VITELIC MSU2051/U2031 product. The product is an 8-bit single chip microcontroller, which is compatible with the 80C51 family. It has a wide range of applications and a powerful instruction set. The product supports 64KB external memory space, 4KB ROM, and 128-byte data RAM. It also provides various hardware features, such as two 16-bit timers/counters, four 8-bit I/O ports, and a full duplex serial channel. The product supports multiple working voltages and power save modes.