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One of my favorite systems is the Colecovision. The core is really pretty awesome and it would be even better with save states. There are a lot of homebrew games that allow high score initials to be put in, but they aren't saved when you change games. Having save states will remedy that issue. What do you think?
There are some great adventure titles that would benefit from save states as well. I see this post has over 700+ views, but no comments. What are your thoughts on this request? Are you in favor of such advancements?
My thought is that any core would be better with save states 
But it's not exactly a novel idea, and I'm pretty sure all the devs are aware of the popularity of such request (just look at the reaction to SNES core). So, it's clearly not a trivial thing to implement, and in some cases probably impossible due to hardware limitations.