The Floppy Disk

IBM's System/370 had a problem that had nothing to do with storing customer data: it needed its own microcode loaded at power-up, and punched cards were slow and enormous. In 1971 a team under Alan Shugart shipped the 23FD, codenamed Minnow — an eight-inch flexible disc in a sleeve, read-only, holding about eighty kilobytes. Its whole job was to boot the machine. The 33FD of 1973 made it read-write, and at that point somebody noticed what had actually been invented. Here was storage you could take OUT and hand to somebody. The hard disks of the day were sealed, or the size of a washing machine, or both. Within a decade the floppy was how software was sold, how documents moved between offices, and how an entire generation of personal computers booted. The engineering choice underneath it is contact. The head rests ON the medium instead of flying above it, which by blueprint 1's arithmetic should be a triumph — zero spacing means zero spacing loss. It is not a triumph, because contact means friction, so the disc must turn slowly, the medium must be soft enough not to grind the head away, and the head must be wide enough not to plough. Every one of those costs density, and together they cost more than the spacing loss they saved. MEASURED, NOT FABRICATED. Nobody coats their own medium. What you can do is develop a real floppy's magnetic tracks with ferrofluid and look at them — the recorded data becomes visible under a loupe, and the track pitch is measurable to a few percent.