日本Sony公司的DDU220E是一种能装人PC机的DVD—ROM驱动器，其最大连续数传率为6750KB／S（即通常所说的5倍速）。这是首台支持SX传输的DVD—ROM驱动器。由于该驱动器是利用恒角速（CAV）方式控制盘的转动，因此，除最外道外，其它轨道上的数据读出速度都低于SX。因为无需调整 Japan’s Sony Corp.’s DDU220E is a PC-capable DVD-ROM drive with a maximum continuous data rate of 6750KB / S (commonly known as 5x speed). This is the first DVD-ROM drive to support SX transfers. Since the drive uses constant angular velocity (CAV) to control the rotation of the disc, the data on other tracks except for the outermost tracks are read out at a rate below SX. Because there is no need to adjust