Electric motor
Stepper motors can be rotated to a specific angle in discrete steps with ease, and hence stepper motors are used for read/write head positioning in computer floppy diskette drives. They were used for the same purpose in pre-gigabyte era computer disk drives, where the precision and speed they offered was adequate for the correct positioning of the read/write head of a hard disk drive. As drive density increased, the precision and speed limitations of stepper motors made them obsolete for hard drives--the precision limitation made them unusable, and the speed limitation made them uncompetitive--thus newer hard disk drives use voice coil-based head actuator systems. (The term "voice coil" in this connection is historic; it refers to the structure in a typical (cone type) loudspeaker. This structure was used for a while to position the heads. Modern drives have a pivoted coil mount; the coil swings back and forth, something like a blade of a rotating fan. Nevertheless, like a voice coil, modern actuator coil conductors (the magnet wire) move perpendicular to the magnetic lines of force.)
What do newer computer drives use instead of stepper motors?
voice coil-based head actuator systems
As drive density increased, the precision and speed limitations of stepper motors made them obsolete for hard drives--the precision limitation made them unusable, and the speed limitation made them uncompetitive--thus newer hard disk drives use voice coil-based head actuator systems.
stepper motors