Scott M. Baker built this Raspberry Pi multi-cartridge for his Atari 5200. The idea is to maintain the experience of the cartridge interface without having to keep stacks of cartridges around for all the games he wants to play.
http://www.smbaker.com/pi-powered-at...idge-multicart
https://hackaday.com/2018/07/26/dual...ole-multicart/
http://www.smbaker.com/pi-powered-at...idge-multicart
https://hackaday.com/2018/07/26/dual...ole-multicart/