Black ops unlock all zombie maps

There are no codes to unlock these maps; you have to pay for them.
The only cheat codes that exist are:
You need to access the terminal to enter them: in the main menu when you're sitting on a chair, press L2 and R2 or LT and RT simultaneously; the terminal is located behind the chair you are sitting on.

3ARC INTEL: See all information
3ARC UNLOCK: Unlock Dead Ops Arcade and the Presidential Zombie mode
alicia: Play Alicia (virtual therapist)
cat: Open audio/image files (e.g., CAT NoteX.txt)
decode: Decode CIA data
dir: Display a list of audio/image files
DOA: Play "Dead Ops Arcade"
encode: Encode CIA data
foobar: Display the message "Fee Fie Foe Foo!" on the terminal
hello sailor: Play Zork
help: Display help
login: Open a new session
ls: Display the contents of the current directory
mail: Open the mail directory
print: Print or show the contents of a file
TYPE: "File_name.extension" See a file
who: Display a list of usable login names with RLOGIN
zork: Play Zork

There you go, see you later!