Once the buffer memory's contents are replenished, the pickup resumes reading the signals at regular intervals. Types of MiniDisc Two types of discs have been developed for the MiniDisc system. Designed specifically for prerecorded music from record companies, playback-only MiniDiscs are similar to CDs in many ways. The lead-in area is on the inner circumference of the disc. This is followed by the program area, while the lead-out area is on the outer circumference of the disc.
Information is recorded as pits in the disc's substrate in much the same way as with full-size CDs.
The discs can be stamped out and mass-produced with an injection molding machine. The entire front of the caddy that protects and holds the prerecorded disc can be used for graphics, since the protective shutter on this caddy opens only on the back side. One of the most important features of the MiniDisc is complete random access capability. On the other hand, random access is harder to achieve on a disc whose final recorded sequence is unknown at the time of manufacture and, indeed, can be changed many times. The pre-grooves molded into recordable MiniDiscs for tracking control have a wobble.