1704主机系统装有两个磁盘,实际上只用一个,另一个作备用。最初,曾设计了一个硬件手动开关,实现了双盘换用,但不能联用,所以实际上仍然是用一个磁盘。为了扩大磁盘容量,使小机器发挥更大的作用,必需实现两磁盘的联用。为此,我们一方面在线路上设计一条DOT1,3硬件指令,将手动换盘开关改为自动换盘开关;另一方 1704 host system is equipped with two disks, in fact, only one, the other for backup. Initially, once designed a hardware manual switch to achieve the dual-use, but can not be used together, so in fact still use a disk. In order to expand the disk capacity, so that small machines play a greater role, the need to achieve the combination of two disks. To this end, we design a DOT1,3 hardware instructions on the line, the manual changer switch to automatic changer switch; the other