NT was a digital memo recording system introduced by Sony in 1992, sometimes marketed under the name Scoopman. The system stored memos using helical scanning on special microcassettes, which were 30 × 21.5 × 5 mm with a tape width of 2.5 mm, with a recording capacity of up to 120 minutes.
NT stands for Non-Tracking, meaning the head moves at a shallower slope to that of the tracks on the tape, crossing several during each pass, albeit only reading partial data from each one. By making several different passes it is possible to reassemble the complete data for each track, in memory. This considerably reduced the complexity and size of the head, and therefore the recorder.
Another feature was Non-Loading, which meant instead of having a mechanism to pull the tape out of the cassette and wrap it around the drum, the drum was pushed inside the cassette to achieve the same effect.
Audio sampling was in stereo at 32 KHz/12 bit and encoded using a form of linear delta modulation called LDM-2.
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