CD3
an 80-mm (3-inch) CD (compact disc)
CD3: the smallest standard compact disc format
A CD3 is a compact disc with an 80-millimetre diameter, the smallest of the three standard CD formats. It holds up to 210 megabytes of data or about 24 minutes of audio at 44.1 kHz sampling. The format emerged in the 1990s as manufacturers sought a middle ground between the full-sized 120-mm CD and specialized mini-CD variants that lacked industry standardization.
CD3 drives and media remained relatively uncommon outside specific applications. Portable audio players, automotive systems, and educational devices occasionally shipped with CD3 capability, but the format never achieved wide adoption in consumer electronics. The smaller physical footprint offered practical advantages in space-constrained equipment, yet the capacity penalty and manufacturing complexity meant producers rarely justified the tooling investment.
The disc itself uses the same polycarbonate substrate, data spiral, and laser wavelength (780 nanometres) as larger CDs, making playback straightforward for drives equipped to handle the smaller geometry. Error correction and audio encoding follow identical Red Book audio specifications. The main engineering hurdle lay in spindle design, track-following mechanics, and firmware to accommodate the reduced radius without sacrificing read reliability.
CD3 media production required dedicated mould tooling and pressing equipment configured for the smaller blank. This made short production runs uneconomical for most manufacturers. The format existed in an awkward space: larger than floppy discs yet smaller and less convenient than standard CDs, and arriving just as USB storage began replacing optical media entirely for portable data transfer.
Today CD3 equipment is essentially obsolete in industrial and consumer contexts. Surviving drives are confined to legacy systems and specialized archival hardware. The format demonstrates how standardization committees can approve variants that market forces ultimately reject, especially when the compromise between capacity and form factor satisfies neither consumers nor manufacturers.