Is there only three Zombie maps in Black Ops including Dead Ops Arcade, or is there more?

Because in the leader board when you first enter zombies it shows six map names, why is this, can you unlock these?Is there only three Zombie maps in Black Ops including Dead Ops Arcade, or is there more?
THere are 3 that we can unlock with the normal edition

BUt there are other maps from cod waw that you can only have by buying the hardened or prestigee edition

but we will be able to buy them with microsoft point soon enoughIs there only three Zombie maps in Black Ops including Dead Ops Arcade, or is there more?
when you complete the game you unlock more maps. their is also a cheat that you enter when your at the computer but i don't know the cheat

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