1.掌握KeilC环境的使用

1）字节拆分、合并：调试e421.asm程序， 观察相关寄存器和单元的内容。

2）数据块填充：调试fill.asm程序，观察相关寄存器和单元的内容。

2. 编写两个十六位数的加法程序。

有两个十六位无符号数，分别存放在从20H和30H开始的数据区中，低八位先存，高八位在后，和存于R3（高八位）和R4（低八位），进位位存于R2。

-Master the environment, the use of 1) bytes KeilC split, merge: debug e421.asm program to observe the relevant register and the contents of the cell. 2) data block fill: debug fill.asm program to observe the relevant register and the contents of the cell. (2) to write two 16-digit addition. Two 16-bit unsigned number stored in the data area from 20H and 30H, the low eight pre-existing high eight in the post, and stored in R3, (high eight) and R4 (low eight ), the carry bit stored in R2.