14．使用移位类指令时，若需移动多位，则应先将移位次数置于

A．AH中                                                                   B.AL中

C.CH中                                                                      D.CL中

15．下列指令中，正确的是

A.MOV  DS, 3000H                                                B.MOV［DI］, ［SI］

C.MOV  AL, ［sI］［DI］                                     D.MOV BYTE PTR ［BP］［SI］,  100

16．设有数据定义语句

DATA  DW  'AB'，  'CD'

则执行指令MOV  AL,BYTE PTR DATA+1后，AL的内容为

A.41H                                                                          B.42H

C．43H                                                                       D.44H

17．用512×4位的RAM芯片构成4KB的存储系统，需要该芯片的数量是

A.4片                                                                          B.8片

C．16片                                                                    D.32片

18．两片8259A级联时，中断源个数最多为

A.8个                                                                          B.15个

C．16个                                                                    D.64个

19.8255A的PA、PB、PC三个端口可分为A组和B组。其中与PA构成A组的是

A.PB_3-0                                                                        B．PB_7-4

C．PC_3-0