The Floppy Disk: From IBM Mainframes to Nuclear Command Systems

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The floppy disk was declared obsolete well over a decade ago, yet it coordinated functions of the United States nuclear forces until 2019 and loaded flight software onto British Airways Boeing 747s until that fleet retired in 2020. This episode starts in 1971, when IBM introduced an eight-inch, read-only disk for loading microcode into mainframes, and follows the format as it shrank to the 5.25-inch mini-floppy from Shugart Associates in 1976 and then to the rigid 3.5-inch design, based on a Sony format, that became the universal save icon.

Along the way come the mechanical details that made the disk both clever and doomed: fabric liners that wiped the surface as it spun, a read head that dragged directly across the iron oxide, and stepper motors that limited how tightly data could be packed. Users answered with hole punchers and power drills. Apple answered with variable speed motors. When software outgrew 1.44 megabytes, the Zip disk and the LS-120 SuperDisk tried to save the format before USB flash drives ended the contest.

• Users punched a notch in single-sided 5.25-inch disks to make flippy disks, since factories coated both sides with iron oxide anyway.
• Early Macintosh drives slowed the motor at the outer tracks and sped it up near the center, storing 400 and later 800 kilobytes where PCs managed 360 or 720.
• Steve Wozniak's Apple II disk controller dropped the track zero sensor, so the drive slammed the head against a metal stop, producing its famous clacking.
• Apple's 1998 iMac G3 shipped with no floppy drive, and Dell stopped including them as standard equipment by 2003.
• A 2016 Government Accountability Office report found nuclear command and control running on eight-inch disks in IBM Series/1 computers, and Japan required floppy submissions for some documents until 2024.