With my good friend Buzz, we spent last past few weeks on a new project called "63 in 1".
This is a home made cartridge with 63 games, an enhancement of our previous "31in1" colecovision cartridge.
All the hardware part is well described on buzz web site, with schematcs and eagle files : here
The loader is a modified version of the 31in1. All the source code is provided under BSD like license here :
It contains also the eprom file i've used for this demo :
Finally this archive contains all files needed to build your own cartdridge (eagle files for the PCB etc ...)
If you are interested in making your own cartridge here is a model you can print :here
For people like me, who don't have the solder skill of Buzz, you may give a try to a 'test board' version, as i did here :