locomotives 6090, 60901, 60903, 60904, with speaker and sounds for steam locomotives. 60932 Decoder upgrade for existing digital locomotives 6090, 60901, 60903, 60904, with speaker and sounds for diesel locomotives. 60933 Decoder upgrade for existing digital locomotives 6090, 60901, 60903, 60904, with speaker and sounds for electric locomotives. mLD and mSD conversion kits, mLD/3 (Märklin LokDekoder) and mSD/3 (Märklin SoundDekoder) In 2015 Märklin released a new series of retrofit decoders built on a 32 bit architecture, compared to 8 bits of the previous generation. The mLD/mSD generation is faster, has more memory, including 64 Mb memory reserved for sound data, as well as improved sound processing. With 4096 speed steps for the motor, and self calibration, motor characteristics, especially at low speeds, are improved. Along with these decoders, Märklin released the 60971 mDP/3, (Märklin Dekoder Programmer), a USB device which allows for easy programming of parameters of the mLD/mSD decoders as well as customizing sounds and images. The firmware of the decoders can be updated. The related software, mDT (Märklin Dekoder Tool) is adapted for Windows platforms. The decoder upgrade kits are not suitable for motors with older field-wound coils. Locomotives with these motors must be converted with the appropriate motor retrofit kits, item numbers 60941, 60943, or 60944. The decoders can be operated with the 6020, 6021, Mobile Station, and Central Station controllers and can be programmed with the protocols MM, mfx, and DCC The retrofit kits come in 3 different formats. All the mSD3 kits come with 2 speaker options, small and large, except for 60978 and 60979, including one speaker. For upgrades to fixed circuit board with a 21 pin decoder interface. 60972, mLD3, circuit board with soldered on wires for the locomotive side and a male 21 pin connector for the included decoder. 60975, mSD3, (Steam) circuit board with soldered on wires for the locomotive side and a male 21 pin connector for the included decoder 60976, mSD3, (Diesel) circuit board with soldered on wires for the locomotive side and a male 21 pin connector for the included decoder 60977, mSD3, (Electric) circuit board with soldered on wires for the locomotive side and a male 21 pin connector for the included decoder For upgrades of 36xxx series Märklin/Trix fixed circuit board locomotives with LED lights. 60978, mSD3, 21 pin connector for the included decoder with pre-loaded Diesel sounds. 60979, mSD3, 21 pin connector for the included