Zone bit recording
Zone Bit Recording (ZBR) is a recording technology for hard disks as well as for some historical disk formats (floppy stations of the CBM series or the C64 / C128).
It is used to store more sectors on the outer cylinders than on the inner ones .
To implement ZBR, a hard disk controller must adjust the write and read rate accordingly. The outer cylinders are read faster than the inner ones. This means that the maximum data transfer rate can only be achieved on the outer tracks of the hard disk.