Sony ES Recordable MiniDisc (74-minute) MiniDisc is a non-contact digital audio format employing magneto-optical technology. Therefore, repeated use has virtually no effect upon performance. It also resists even strong magnetic fields which would ruin a tape recording. Sound effects, musical themes, commercial messages, and announ-cements can be recorded in stereo or mono on up to 255 tracks for individual, rapid access. Maximum recording/playback time is 74 minutes. The block error rate (BLER) of the PRMD series remain extremely low, unaffected by even one million erase/read/write cycles.