5.25 inch Floppy Disk

In 1976 at a meeting An Wang of Wang Laboratories informed Shugart Associates’s, Jim Adkisson and Don Massaro, that the 8-inch format was simply too large for the desktop word processing machines he was developing at the time. Adkinson and Massaro proposed a 5¼-inches wide format which Wang accepted. Shugart Associates then developed a new drive of this size storing 98.5 KB later increased to 110 KB by adding 5 tracks. The 5¼-inch drive was considerably less expensive than 8-inch drives from IBM, and soon started appearing on CP/M machines. At one point Shugart was producing 4,000 drives a day. By 1978 there were more than 10 manufacturers producing 5¼-inch floppy drives, in competing physical disk formats: hard-sectored (90 KB) and soft-sectored (110 KB). The 5¼-inch formats quickly displaced the 8-inch for most applications, and the 5¼-inch hard-sectored disk format eventually disappeared.
Apple introduced the 5¼-inch Disk II for the Apple II in 1978, using GCR encoding to store 35 tracks of 13 sectors of 256 bytes (113KB). An upgrade to a more sophisticated GCR scheme in 1980 increased track capacity to 16 sectors (140KB for the disk).