Everyone knows that the IBM PC established 512-byte sectors on floppies and hard disks as the standard, which survived for several decades until the advent of “native” 4K-sector drives.
Of course what “everyone knows” is not necessarily the whole story.
PC Floppy Sector Sizes
The original 1981 IBM PC Technical Reference says: The [IBM PC floppy] drives are soft sectored, single sided, with 40 tracks. They are Modified Frequency Modulation (MFM) coded in 512 byte sectors, giving a formatted capacity of 163,840 bytes per drive.
But that was never really true; while PC DOS 1.0 indeed used 8 sectors per track, resulting in 163,840 bytes (512 × 8 × 40 bytes) on a floppy disk, PC DOS 2.0 supported 9 sectors per track on the same hardware, with increased 184,320 bytes disk capacity. This was possible in large part because the BIOS in the IBM PC was fairly flexible when it came to floppy disk formats.
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