OP, I understand how you feel, but please read carefully: do NOT make a big deal out of this.
If your dad has decided that you can't have a computer in your bedroom, that's his choice. Ask him why, and if he gives you a reason that's even half plausible (scared of sexual predators, porn, etc) then just drop it. It isn't in your interest to fight this battle at this time. You would do better to wait until you're slightly older and then try again.
Out of curiosity, how old are you? I'm guessing 13 or 14 since you wrote "teenager" in your OP. For your dad, allowing you to have a computer in your room is probably a scary thought. You have to change that by earning his respect. Show him you're responsible and he might allow you to have it back. Either way, always remember that it's his choice, and that if you want it back, you need to convince him by proving it to him, not by engaging in a yelling match.
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If you want to know how to manipulate fathers into giving you what they want (totally off the record btw) you need to trick them into thinking that your idea is really their's. For example, you might start by getting your dad to express a feeling of frustration at the fact that the mini is in the living room. You might accomplish this by using it more often and showing how "obtrusive" it is to have a mini in the living room. You then suggest another room in the house (knowing it can't go there at all) and then let him sit on it for a while. If you know how to manipulate well enough, you can get your dad to give you that mini within six months.
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