Fixed-head disk

Fixed-head disks were magnetic disks which had a separate head, fixed in position, for each track. They were direct descendants of drums, a prior secondary storage technology, which also had a head per track.

This avoided the delays involved in having the head(s) seek to the correct cylinder, and was also mechanically simpler, but did require more components.

The platters of such disks were generally not removable, which meant they also did not require exact alignment (if you did not care about being able to read the previous contents after servicing).