Combined with braking and acceleration delay (artificial inertia) these decoders give smooth and exact speeds with reliable slow speed control.
A number of different digital systems were developed, but Märklin Digital and DCC (Digital Command Control) are the two main systems on the market.
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 red Stop button was provided as an emergency stop to immediately halt all trains.
The 6043 could save up to 24 different routes, which each route containing up to 20 individual device commands.
For multiple trains sidings must have a switch to isolate trains standing there and leave the track dead.
For multiple controllers the layout must be divided into sections isolated from each other and each with its own controller and current supply.
Once a locomotive is running it will continue and so even with one controller several trains can be running.
Many locomotives may be on the track and individually controlled.
Up to ten controllers could be added to the right hand side of the Central Unit, and up to 16 keyboards could be added to the left hand side, with each keyboard controlling 16 accessories (signals, turnouts, lights, etc.) for a total of 256.