1. halt
                                                   2. SSCOP: mov [KEY1], 3ah
                                                   3. mov X, SP
                                                   4. mov A, X
                                                   5. add A, 3
                                                   6. mov [KEY2], A

other feature;

These aid in the determination of success or failure of a particular function. The return code is stored in KEY1’s position in the parameter block. The CheckSum and TableRead functions do not have return codes because KEY1’s position in the parameter block is used to return other data.

Return Code Value                         Description
00h                                                 Success
01h                                                  Function not allowed due to level of protection on the    block.
02h                                                  Software reset without hardware reset.
03h                                                  Fatal error, SROM halted.

这些函数好像比较少的用到....   具体的说明在   P72 OF TRM