Halo: Combat Evolved Anniversary

TERMINAL LOCATIONS:

Pillar of Autumn:
At the beginning of the level make you're way to the bridge. After talking to Keyes and regaining control of the chief, find the glowing red computer console to find the terminal.

Halo
After entering the underground tunnel, proceed like normal, but instead of jumping the gap like normal, find a small side tunnel in the immediate area and you'll find the terminal at the end of it.

Truth and Reconciliation:
After defeating the Zealot on the Bridge, use the red console on the raised platform in the center.

Silent Cartographer
When heading for the Security Building, you'll encounter two hunters in the center of the island. The terminal will be located on the wall of the structure in the center of this area.

Assault on the Control Room:
Toward the end of the level you will come to the Pyramid with the Control Room at the top. You'll notice a long, flat piece of the structure running straight down the middle of it and going into a crevice in the ground below. Go inside this crevice and you'll find a terminal mixed in with a large amount of hidden ammo supplies.

343 Guilty Spark:
After making your way to the Elevator that will allow you to escape the underground facility, you'll find the Terminal above the doorway you came out of. It can be reached by activating the Elevator, than timing it correctly and jumping off onto the platform below (this may take a few attempts, but the elevator can be activated as many times as needed.)

The Library
On the third floor, you'll come to a room with a large circular room (the Index platform will be above it. Go right and use the crouch jump to jump over the barriers and you'll come to a room that looks like the rest of the level, but is disconnected from the regular game. The Terminal will be plain as day before you even reach it.

Two Betrayals:
In the control room at the beginning of the level, walk around the the circular platform and you'll find the terminal directly across from the control console.

Keyes:
After find Keyes absorbed into the Proto- Gravemind, kill the Covenant and Flood that attempt to ambush you, than search the sunken crevices to the side of the raised platform. The terminal will be down inside one of the two.

The Maw:
Play the level like normal until you reach the Cryogenic Storage Bay where Sentinels will be busy fighting the Flood. A glowing Control console on the wall will house you final terminal.

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I can confirm that it does NOT have to be in one playthrough. And you don't need to watch the whole thing.

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BONUS! I've also included an extra video (by Nak3d Eli) for the 11th terminal through Halo Waypoint, which nets you 100,000 free credits. It isn't required for the achievement.

You need to be in HD mode to see the terminals. (Press "select" if you're in location and the terminal isn't showing.) You don't need to watch the video at all—just enter it. (You can always view them from the Extras menu.) Press your action button to use the terminal (X in regular mode, B in Bumper Jumper).

NO SPOILERS

Terminal 1: Pillar of Autumn
Upon arriving at the bridge (where you meet Keyes), walk around the left side for the flashing red terminal. If you miss it, you can return after Keyes shuts up, or even after receiving the pistol.

Terminal 2: Halo
When in the underground complex in the Warthog before making the gap jump, a hallway glows with a yellow terminal. It's hard to miss if you just follow the path.

Terminal 3: Truth and Reconciliation
In the bridge room (with the elevated platform with lots of screens) before reaching the jail cells, the terminal is the red screen directly ahead on the platform. For an audio cue, Cortana will say that Keyes's "transponder signal is strong."

Terminal 4: The Silent Cartographer
After passing into the path in-between the rocks en route to the override, the clearing with the two Hunters (big spiky guys with who shoot green Fuel Rod shots) holds the terminal. It's blue and up against the left side of the central structure's pillar.

Terminal 5: Assault on the Control Room
At the end of the level with the pyramid-like structure, make a left towards the crag in the ground instead. The blue terminal lies against the back of the base of the gray structural support entering the ground. (If you steal the Banshee earlier for the achievement, you can fly directly to the ground to skip the elevator segment.)

Terminal 6: 343 Guilty Spark
Read this first. There are three elevators in this level—the one down into the structure, the one that's broken, and the one that goes up at the end. After activating the FINAL lift (up), run back for the entrance whence you came. The yellow terminal is atop that doorway structure.

Terminal 7: The Library
On the third flood of the Library with the gigantic circular void in the ground, you'll see a yellow light flashing across the way. Jump over the spokes around the void to reach the yellow terminal.

Terminal 8: Two Betrayals
At the beginning of the level, walk to the other end of the circular platform for the yellow terminal.

Terminal 9: Keyes
In the bridge room (from terminal three), enter the trench in the ground closest to the jail cells. What do you know? A red terminal has sprouted!

Terminal 10: The Maw (last one)
In the room similar to the one that started the game, after climbing the ladder and encountering the Sentinels (flying laser bots), check out the technology where the Sentinels were flying: the final red terminal.

I put together this video of all the terminal locations in halo anniversary i also have a skull guide on my channel if you would like to check that out