The initial system was presented at the 1979 Nürnberg International Toy Fair, released in Europe in 1985 and the USA in 1986 under the name Digital H0.
All accessories such as signals and turnouts require individual switches and cables, making wiring very complex.
The track consists of 2 electrically-grounded rails, and a row of center studs over which the engine's pickup "shoe" glides acquiring the digital-pulsed 16V signal and power.
The Motorola based system was officially introduced in 1985, developed by a relatively unknown electronics contractor with most components built by Märklin.
In subsequent years, another contractor, Bernd Lenz, would also work on the system producing locomotive decoders and, later, Märklin's first DC command control offering.
[3] Electronics of the time were relatively expensive and the system used ternary logic to reduce the number of components and cost of devices.
Early decoders cost as much as many model locomotives and the expense of upgrading an existing layout was considerable.
The original 6020 Central Unit provided track power & generated locomotive commands but required a separate 6035 locomotive Control 80 with speed controller, keypad for decoder address, Function / Off buttons, and Start / Stop buttons to switch track power.
The s88 would receive input signals from external buttons or magnetic reed switches and then start a command string in the 6043 Memory.
Decoders had miniature switches (DIP switches) to set the address and c90 decoders had two potentiometers to adjust braking / acceleration delay ("inertia") and maximum speed, requiring the use of tools to open the model and make any changes to settings.
Signals, turnouts, uncouplers, lights, and other static accessories may also be fitted with decoders which have their own address range for up to 256 switched devices.
Depending on the decoder, either continuous power (lighting) or momentary (signal, uncoupler, turnout) is provided.
Automatic braking allows a locomotive to coast relatively gently up to a stop signal at danger.
Older c90 decoder equipped locomotives will always restart forwards after power off, regardless of the previously controlled direction.
Miniature switches set the operating mode (old or new protocol) and reduced track voltage for shunting areas.
1997 c91 (60901) decoders provided additional function outputs F1 - F4, 27 speed steps (stop 0 and 1 - 27), and improved motor regulation.
While the small size of speaker that can be fitted into H0 locomotives limits reproduction, built in sound has become a feature of many models.
DELTA has now been discontinued, simplified digital controllers & decoders are offered instead (Mobile Station & 36xxx series locomotives).
For steam locomotives, additional parameters such as boiler pressure and fire state can be set, monitored, and controlled.
The hand held Mobile Station 60652 was also offered which has a single locomotive controller, small LCD screen, and 9 function buttons.
In 2008 Märklin announced a new second generation Central Station 60213 with colour display and enhanced features, this unit developed by a different contractor.
Central Station 3+ adds the ability to act as a master unit in a multi controller set up.
mfx decoders can also interpret the older Motorola format and so will work with previous central units.
Märklin experienced compatibility problems with the first Central Station (CS1) leading to a recall and extensive rebuild resulting in CS1 V2.
A digital decoder was the basis and many kits also included a permanent magnet and 5 pole armature to upgrade the motor and convert it to DC (such decoders rectify track current to DC for the motor and any accessories, such as lighting or sound).
For many years, unlike Digital Command Control, Märklin did not use a plug in connector for the decoder and so conversion involved soldering output wires.
DELTA decoders never provided motor regulation and originally had to be set to address 0 for analog operation.
All mfx decoders provide motor regulation with 128 speed steps and multiple adjustable parameters, plus 16 switched functions.