The application '!SignalBox' is a full, accurate simulation of a mechanical signalbox. What does that mean? When I say simulation I do mean a full, accurate simulation, not like some of those on the market! In the simulation, you see the signal box lever frame, block shelf and instruments and track diagram in one window. The working timetable showing the trains that will run is available separately but the train register book, which records the trains that pass from box to box, is shown on screen in another window. The track circuit indicators on the box diagram and the train register are both displayed and kept updated by the computer.

All interlocking, both mechanical and electrical, is fully implemented using original technical data as source data. Context sensitive help messages lead an inexperienced user through the process and the level of difficulty can be selected. The points and signals on the track diagram may be operated by a simple mouse click over them. If interlocking is not free a helpful message is given explaining why the lever or electric lock cannot be operated.

As trains move from track circuit to track circuit, lamps light up on the track diagram, and an image of the train concerned moves over the track diagram on both track-circuited and non-track-circuited lines showing the position of every train continuously. A right-mouse-click over an occupied track will give a menu permitting the engine to be reversed or the stock uncoupled. Context-sensitive help messages will give additional information about whatever the mouse pointer is pointing at. Simulation speed can be adjusted at any point and the simulation paused.

Full simulation (i.e. with a choice of train services) is implemented of either Kidderminster Station (SVR, circa 1998) or Exeter West (circa 1963 but using a train service based on Summer 1982. Also provided are Morlais Junction, Morlais Junction, Radyr Junction (as at 1961, 1984 and 1987) and Bewdley North (1956), which may be operated as a ground frame.

In the full version Rotherwas Junction and Acton Yard, as well as the other SVR boxes, may be operated as ground frames and many alternative timetables are provided for Exeter West and Kidderminster.