I'm using this example because it's genuinely complex, but simple enough that you should be able to get it.
Other people have mentioned the 555, and that's a nice IC to experiement with because they're cheap and simple and versatile and you can see the output easily with any oscilloscope you buy.
So, not quite what you're asking for, but
Have a read of this: http://research.cs.tamu.edu/prism/lectures/mbsd/mbsd_l16.pdf
And watch this video: https://www.youtube.com/watch?v=4dWNP6igNCY
Then look at this circuit diagram and create a memory map for the ram from it. https://github.com/jefftranter/68000/blob/master/TS2/v2/ts2....
I'm using this example because it's genuinely complex, but simple enough that you should be able to get it.
Other people have mentioned the 555, and that's a nice IC to experiement with because they're cheap and simple and versatile and you can see the output easily with any oscilloscope you buy.