Second version of the the-Tandberg-cassette-recorder which would see many versions : TCD-310 MkII, TCD-320, TCD-330, TCD-340A, TCD-440A, TCD-420A, with goodies throughout such as soft-touch transport controls, azimuth & bias correction, 3-heads and Type IV tape as early as 1978 !
The last version, TCD-420A, brings us to 1982, which is when Tandberg made its best but had no more room to develop and sell, cornered by the japanese as everybody else was.
The TCD 310 is based on a 3-motor closed-loop dual capstan drive with two Ferrite heads, a Dolby noise-reduction and even a "special" selector for CrO2 / Type II tape. Motors are two AC for the reels and one hysteresis synchronous for the capstan.
Added was an auto-adjustable input amp which maintains dynamic range and keeps noise low whatever the source recorded : line, microphone or radio.
Otherwise, bar cosmetic differences and marginally better S/N ratio, the TCD 310 seems entirely equivalent to the original TCD-300...