Mission: Tip of the Spear, Rally Point Alpha
This fourth data pad’s located in the mining facility - to skip directly there, simply load up the mission’s Rally Point Alpha. Soon after you hear the Spartans discussing the optional Elite Zealot objective, you’ll drop through this hole in a building’s roof. Continue through to the last interior room and look for the data pad on a shelf behind some boxes. If you end up back outside with the red Revenant vehicle, you’ve gone one door too far.
Mission: Long Night of Solace
Start the mission, cross the beach, enter the launch facility. When you reach the final room before the launch pad - you know, the one with the big blue hologram table in the middle? - check the glowing red area to the side, up a tiny set of stairs. The fifth data pad is on the floor, in front of the computer console.
Mission: Exodus, Rally Point Alpha
Wait until the Bullfrog squad gives you a jetpack, then jump across the chasm with them. On the other side, fight through the Grunts, Jackals and Brutes and climb the stairs. Moving forward, you’ll encounter a dark corner with three Brutes (one in gold armor), two fenced columns and a small L-shaped catwalk near the ceiling. Jetpack up there for the sixth data pad.