Editing Hard disk drive (section)

=== 1980s–1990s ===
Over time, as recording densities were greatly increased, further reductions in disk diameter to 3.5" and 2.5" were found to be optimum. Powerful rare-earth magnet materials became affordable during this period and were complementary to the swing arm actuator design to make possible the compact form factors of modern HDDs.

As the 1980s began, HDDs were a rare and very expensive additional feature in PCs, but by the late 1980s, their cost had been reduced to the point where they were standard on all but the cheapest computers.

Most HDDs in the early 1980s were sold to PC end users as an external, add-on subsystem. The subsystem was not sold under the drive manufacturer's name but under the subsystem manufacturer's name such as [[Corvus Systems]] and [[Tallgrass Technologies]], or under the PC system manufacturer's name such as the [[Apple ProFile]]. The [[IBM PC/XT]] in 1983 included an internal 10&nbsp;MB HDD, and soon thereafter, internal HDDs proliferated on personal computers.

External HDDs remained popular for much longer on the [[Apple Macintosh]]. Many Macintosh computers made between 1986 and 1998 featured a [[SCSI]] port on the back, making external expansion simple. Older compact Macintosh computers did not have user-accessible hard drive bays (indeed, the [[Macintosh 128K]], [[Macintosh 512K]], and [[Macintosh Plus]] did not feature a hard drive bay at all), so on those models, external SCSI disks were the only reasonable option for expanding upon any internal storage.