1980: Entering The Modern Era With The 5.25-inch Drive
Shugart Technology, which was founded by early hard drive pioneer Al Shugart and which eventually became Seagate Technology, in 1980 introduced the ST-506, the first 5-1/4-inch form factor drive.
The ST-506, which initially stored 5 MBs of data, brought the idea of a separate disk controller inside the computer system to the storage industry. By moving the controller from the disk drive to the computer, it was possible for the hard drives to be sold for use with multiple brands of computers. IBM's adoption of the ST-506 drove industry-acceptance of the separate controller.