"3.5-inch" drive: (4 in × 5.75 in × 1 in = 101.6 mm × 146.05 mm × 25.4 mm) This smaller, 4 inches disk-drive form factor was introduced with the Apple Macintosh series in 1984, and later adopted throughout the industry beginning widely with the IBM PS/2 series in 1987, which included drives of this size for 90-mm ("3.5-inch") floppy disks.