说明：  1、 编程完成显示程序，要求在实验箱BANK2部分数码管上显示“1234”，请认真阅读电路，计算出段码锁存器和位选锁存器的地址，显示程序仍然按照“送段码、送位选、延时、消隐”的十字方针进行控制，只是控制的方法不同了，此时锁存器的LE端口由地址总线控制。 2、 根据实验箱BANK2部分电路，完成由8255的I/O扩展操作，在8255A的PA口上接有8个发光二极管，在其上完成一流水灯程序。 3、 根据实验箱BANK2部分电路，完成由8255的I/O扩展操作，将8255A PB口上外接的拨码开关状态显示在PA口的发光二极管上，当开关打开时发光二极管亮，开关关闭时发光二极管灭掉。 4、 完成对片外RAM的读写操作，将自己的学号写入片外RAM 5000H—500AH地址单元，然后将学号的后4位读出，显示在数码管上。
(1, programmed to complete the display program requirements in the experimental box BANK2 part digital tube display " 1234" , please read carefully the circuit calculated Segment latch latches and bit-election address, show the program is still in accordance with the " send segment send Choice, delay, blanking " Cross policy control, but the control of different methods, LE port latch is controlled by the address bus. 2, according to the the experimental box BANK2 part of the circuit, completed by the 8255 I/O expansion operation, then eight light-emitting diode 8255A port on the PA, and completed on a light water program. 3, according to the the experimental box BANK2 part of the circuit completed by the 8255 I/O expansion operation, the 8255A PB port on the external of the DIP switch status display on the PA port of the light-emitting diode, when the switch is turned on light-emitting diode light, the switch is closed glow diode exterminate. 4, complete the on-chip RAM)