设存储单元A和B各有一带符号字节数，比较大小和正负，要求将较大数送RES1单元；如果有负数，将一个负数送RES2，否则RES2送-1-Set storage units A and B each have a signed bytes, compare the size and negative, require a large number of delivery RES1 unit if negative, would send a negative RES2, otherwise RES