- In the Hopeville silo bunker; in the hallway just after you unlock the silo doors.
- In the Hopeville Missile Base HQ; under a desk.
- In the Ashton Silo Control Station behind a locked door, level 1 silo; hack the (hard) terminal next to it.
- In the Municipal Sewers connected to the Third Street Municipal Building offices. Enter the pipe you'll see at the north-west side of the building.
- Near the Cave of the Abaddon, behind the warhead south-east of the Cave entrance. Once you've detonated the warhead, it's on the ground to the north east of the pipe's top opening.If you already destroyed the warhead and missed the ED-E upgrade fast travel once again to the Cave of Abaddon and turn back outside. You should see a fallen sign with red letters to your left. Climb up the debris to find it. If you crossed two electric posts you've gone too far (again these posts are to your left).