Compatibility
Most tray-loading CD devices have 2 'wells'; one sized for a regular 120 mm CD, and a smaller, deeper well for MiniCDs to fit into, except for some blu-ray players.
Devices that feature a spindle also support MiniCDs, as the disc can simply be placed onto the spindle as with a normal CD.
Some vertically aligned tray-loading devices, such as the older pre-slimline PlayStation 2 consoles when placed vertically, require an adapter for use with 80 mm CDs.
Most slot-loading CD drives are generally incompatible (the PlayStation 3 and Wii are exceptions), but adapters are available into which one can snap an 80 mm round miniCD in order to extend the width to match that of a 120 mm CD, and thus work in many slot-loading devices. There are no adapters for business-card sized CDs.
A popular adapter model, Memorex 30183001, was discontinued in 2006.
Most CD players in the late 1980s and early 1990s didn't handle the CD3 well and required the use of an adapter, or very careful placement of the CD in the exact middle of the tray. Not until after the major record labels discontinued them, did the CD Players start to have the CD3 wells as standard.
Since the mid 1990s, all tray loading players have wells for the CD3.
Read more about this topic: Mini CD