A 3.5" floppy disk that holds 800K of data. First introduced on the Apple II line of computers with the UniDisk 3.5 drive. Was later used on the Macintosh. To save money, 3.5 drives used on PC's were based on CAV, so they could store only 720K of data, as opposed to 800K on the CLV 3.5 drives used on Apple machines. 800K floppies were later obsoleted by 1.44MB HD floppies.