I started building a layout in the former bedroom, when I inherited my grandmothers flat in 1979.
The layout consisted of two levels. The bottom level had to be build first and had a good run-in before continuing. In effect the layout worked as if "Y"-shaped with one branch overhead only and the other branch centre-stud only. The bottom leg of the "Y" consisted of a circle with a station with both overhead and centre-stud power.
The layout was build with analogue control. The two dead-end stations at either end of the branches of the "Y" each became a very advanced interlocking attempting to look-alike the electro-mechanical interloking then in use on many stations. Rotary radio-like switches wich could be turned 90 or 180 degrees were bought and used with a surprisingly small number of relais to make a reasonable interlocking. Of course the radio-buttons weren't mecnically locked, but if worked out of sequence a buzzer sounded a the point wouldn't turn. Signals were also set with rotary switches wich energized a holding circuit on a single-coils relais. The power came from a small capacitor, wich was beeing charged when the rotary switch was in the uprigt posistion thus ensuring that the signal handle must be restored to its normal position between each train.
Some years later the layout went digital - in stages. At first only decoders for points and signals were bought, retaining analogue control of the locomotives. The circle and the two lower stations were fitted with computerized interlocking while the upper station retained analogue control to the very end. A special relais was installed to interface with the block on the adjoining line.
The software was written in PolyPascal on a Z80A computer connected to a serial display.
On top of the interlocking programme, I wrote a module for operating in "automatic" mode. If an address number was entered into a track section, this number would follow the train and set the route(s) neccesary to reach the destination appointet by the address. Inspiration came from the system then in use in the powerbox in Nykøbing F.
I bought at digital locomotive and a control 80 assuming I could operate a mixture of digital and analogue locomotives on the layoout, but it soon became obvious that it didn't work and for the final years the layout was operated in digital only.
Borgmester Godskesens Plads 3, 2 left flat, 2000 Frederiksberg (Copenhagen)
Pictlinx ver 3.3 with random access slideshow - www.hjelmenet.dk/software - 20130701 13:56