Halo: The Master Chief Collection - Halo 2 - Fascinated - Halo 2: Activate Terminal 5 on The Oracle. This achievement is fairly easy to unlock.
On the mission The Oracle, you will reach an area where you have to break the glass and drop down where there are flood and covenant.
Drop down and head to the left, all the way to the end where the terminal is located against the wall.
Run over and interact with it and your achievement should pop! Enjoy!