History (1983): 3.5-Inch HDD

This article was published by the Museum of Obsolete Media.

3.5-inch hard disk drive (1983-)

HDDs consist of one of more rigid disks (or platters) with magnetic heads arranged on a moving actuator arm to read and write data to the surfaces.

The 3.5-inch form factor HDD is one of the two dominant types on the market, with the other being 2.5-inch.

The 3.5-inch form factor HDD was introduced by Rodime, a Scottish company, in 1983. Rodime already built HDDs using the 5.25-inch form factor, but introduced the smaller size that utilised the form factor already introduced for 3.5-inch floppy disk drives.

The first 3.5-inch HDD had a capacity of 10MB.

After its introduction, many competitors introduced HDDs using the 3.5-inch form factor, and Rodime sued many other disk manufacturers for infringement of its patents.

Whilst called 3.5-inch, the drives occupy a space 4-inches wide, and were initially 1.6-inches high (the same as the then current half-height 3.5-inch floppy disk drives), but the most popular size today is the 1-inch high slimline or low-profile version.

As of 2014, the largest capacity 3.5-inch hard disk drive is 10TB, equal to 1,000,000 times the capacity of the first disk.

Whilst not strictly speaking removable media, 3.5-inch hard disk drives form the basis for many external HDDs such as those connected by USB, and docks are available to read many HDDes without installing them.

SSDs using flash memory are beginning to replace HDDs for uses where speed, power consumption and durability are more important considerations, such as in tablet computing.