Stella Cartridge Mode PCUAE Atari2600 Plus
This is me playing a round with it.
First thing it does in the video is load a backup of the cartridge(Yars Revenge - 10 in 1 Games Cart) it last dumped so if you have no cart in the slot it will load a backup of the last cartridge it dumped.
I made it so it loads Stella when its loaded a Cartridge instead of Retroarch, and if you exit the game it loads Stella Mode after so you can get to Stella's settings.
On the left screen is Putty, you should be able see it read a cartridge, it copies the dump as a back first so if you want to load it back up again without the cartridge in it you can but if you change the cartridge then the game will change that loads up.
You see me change to different carts and it will change the games to Pac Man and then Mrs Pac Man.