Recreation of a standard ROM cartridge for the CP400 Color Computer,  a TRS-Color compatible manufactured by Prologica .  (Github link)

The schematics and the board were reverse engineered from the pictures and article from Rafael Ferrari (thanks!) 

I like to superpose the bottom and top pcb images to figure out the connections using Libre Office Draw. Other programs can be used as long as they provide to adjust the transparency of the images.

I was intrigued by the bodge wires used on the original cartridge but after analyzing the schematics I could see no reason why the jumpers on the board were not used.

The circuit uses a BJT with a speed-up capacitor on its base to form an inverter for the address line A13 that is used to select either chip is active. That was a very common trick in the 1980s to save on glue logic chips. While such components were not present on the board, it was easy to figure this out given the application.