Caddy (hardware)

Caddy (hardware)

In computer hardware, a caddy refers to a sheath used to hold some media. If the medium is a hard disk drive, the caddy is also referred to as a disk enclosure, which is discussed there. It also refers to optical disks, such as CD-ROMs, which are the focus of this article.

The purpose of a disk caddy is to protect the disk from damage when handling; their use dates back to at least the Capacitance Electronic Disc in 1976, and they were used in initial versions of Blu-ray Discs,[1] though newer versions use hard-coating technology to prevent scratches and do not need a caddy.

Caddies may be an integral part of the media as in some DVD-RAM discs, or separately attached.


A CD caddy being inserted into a Macintosh Centris 660AV

Caddies date at least to the Capacitance Electronic Disc, which used a caddy from 1976 to protect the grooves of the disc.[2]

Two Compact Disc caddies

Some early CD-ROM drives used a mechanism where CDs had to be inserted into special cartridges or caddies, somewhat similar in appearance to a jewel case. Although the idea behind this—a tougher plastic shell to protect the disc from damage—was sound, it did not gain wide acceptance among disc manufacturers. Drives that used the caddy format required "bare" discs to be placed into a caddy before use, making them less convenient to use. Drives that worked this way were referred to as caddy drives or caddy load(ing), but from about 1994 most computer manufacturers moved to tray-loading,[3] or slot-loading drives.

The same system is still available for more recent formats such as DVD-RAMs but is not common.

The PlayStation Portable, UMD disc is a similar concept, using a small proprietary DVD-type disc, in a fixed unopenable caddie as both a copy protection and damage prevention measure.

The MiniDisc is a similar concept again, using a small proprietary Magneto-optical type disc instead, also in a fixed unopenable caddy.


  1. ^ Blu-ray Disc Founders (2004-08). "White paper, Blu-ray Disc Format, General" (PDF). Retrieved 2009-04-16. 
  2. ^ "Comparison of 1977 CED Media to Final Production Media". Retrieved 2007-03-10. 
  3. ^