Editing Floppy disk (section)

====Finding sectors====
All 8-inch and some 5¼-inch drives use a mechanical method to locate sectors, known as either ''hard sectors'' or ''soft sectors'', and is the purpose of the small hole in the jacket, off to the side of the spindle hole. A light beam sensor detects when a punched hole in the disk is visible through the hole in the jacket.{{fact|date=June 2024}}

For a soft-sectored disk, there is only a single hole, which is used to locate the first sector of each track. Clock timing is then used to find the other sectors behind it, which requires precise speed regulation of the drive motor.{{fact|date=June 2024}}

For a hard-sectored disk, there are many holes, one for each sector row, plus an additional hole in a half-sector position, that is used to indicate sector zero.{{fact|date=June 2024}}

The Apple II computer system is notable in that it does not have an index hole sensor and ignores the presence of hard or soft sectoring. Instead, it uses special repeating data synchronization patterns written to the disk between each sector, to assist the computer in finding and synchronizing with the data in each track.<ref>{{cite book |last=Brenner |first=Robert C. |title=The Apple II Plus/IIe Troubleshooting & Repair Guide |year=1984 |publisher=Howard W. Sams & Co. |url=https://vintageapple.org/apple_ii/pdf/Apple_II_Plus_IIe_Troubleshooting_%26_Repair_Guide_1984.pdf}}</ref>

The later 3½-inch drives of the mid-1980s do not use sector index holes, but instead also use synchronization patterns.{{fact|date=June 2024}}

Most 3½-inch drives use a constant speed drive motor and contain the same number of sectors across all tracks. This is sometimes referred to as [[Constant Angular Velocity]] (CAV). In order to fit more data onto a disk, some 3½-inch drives (notably the [[Macintosh External Disk Drive|Macintosh External 400K and 800K drives]]) instead use [[Constant Linear Velocity]] (CLV), which uses a variable speed drive motor that spins more slowly as the head moves away from the center of the disk, maintaining the same speed of the head(s) relative to the surface(s) of the disk. This allows more sectors to be written to the longer middle and outer tracks as the track length increases.{{fact|date=June 2024}}