A.3F8H-3FFH B.2F8H-2FFH C.378H-37FH D.20H-21H
A.2 B.4 C.6 D.8
A.查詢(xún)輸入/輸出 B.輸入緩沖、輸出鎖存 C.無(wú)條件輸入/輸出 D.雙向數(shù)據(jù)傳送
