CH551G development board features the CH551 chip, which is an enhanced e8051 core single-chip microcomputer compatible with MCS51 instruction set. 79% of its instructions are single-byte single-cycle instructions, and the average instruction speed is 8-15 times faster than the standard MCS51.
More information:
https://www.seeedstudio.com/CH551G-Development-board-p-4764.html