Kenwood DM-SG7 - Manual (Page 10)

DM-SG7(EN)
10 MD system
The Mini Disc system has the features as summarized in the following.
1 Like CD (Compact Disc), playback can be started from any position. (Random access)
2 It uses a disc with a diameter of 64 mm that is accommodated in a cartridge.
3 Two types of discs can be used. (playback only discs, recordable / playable discs).
4 Up to 80 minutes of recording or playback is possible using high-efficiency coding technology.
5 Countermeasure against vibration is taken using semiconductor memory chip.
Playback-only Mini Disc
This type of MD can be used only for playback, and is used by the commercially-available music MD software packages.
The playback-only MD is an optical disc like the Compact Disc (CD). The signals are recorded as the presence or absence
of small pits and read out by an optical, non-contact pickup.
Recordable Mini Disc
This MD is a magneto-optical disc which can be recorded by magnetic field modulation. To record signals, laser light is
irradiated from the bottom side of the magneto-optical disc and magnetic field is applied from the upper side of it.