A Fast Clock is exactly what its name implies: A clock which runs faster than normal.
Its purpose is to compress time for realistic model railroad operations. Trains run to a schedule, but in a compressed world, time enhances the illusion when it passes faster than it normally would in real time.
DCC and Fast Time Clocks
Many Digital Command Control systems possess the ability to display a fast clock, with the user able to set the desired ratio. The ratio can be 1:1, or up to 1:5.
Pressing the CLOC key on a Digitrax throttle displays the time, which is also available on LocoNet to sync all the throttle's time.
NCE also offers a fast clock on their throttles with a display. The time is also broadcast on the Cab Bus.
A number of manufacturers offer fast clocks which interface with the throttle network to provide time. In these situations the command station acts as the master reference for time on the network.
JMRI also offers a fast clock. It can be provided using the computer's internal clock, or synchronised to the throttle or LCC bus. A number of styles are offered.