有20个无符号数存放在内部RAM从41H开始的存储单元中，试对他们求和并将结果存放在40H单元中（设和小于等于255）-There are 20 unsigned number stored in the internal RAM storage unit from the beginning of the 41H, test for them and the results are stored in the 40H summing unit (set and less than or equal 255)