Cooking pasta in the Instant Pot works great because you don't have to drain it. For some reason it seems like it swells, a half a pound of pasta is plenty for two people.
Your ratio is 4 cups of water to 8 ounces, half a box of pasta. How long you cook it depends on the type of pasta you use, Look on the box, if it says 8-10 minutes, cook it for 4 or 5 minutes. You cut the cooking time in half
When the cooking is finished, do a quick release and stir. It may seem watery at first, but as you stir it, the water absorbs into the pasta.
So easy and it never sticks, never boils over, it just works!