During the Crysis 3 Mission 3: The Root of All Evil, you can collect four Datapads.
Once you reach the top of the dam, you will see two buildings. In the first one, see the screenshot below, hack the door, and you will find a datapad on the ammo crate.
Datapad no. 2 and no. 3
Near the end of the mission you will use the elevator to get inside the CELL System-X Harvesting Facility. Once you exit the elevator, turn left, and follow the path which leads to a computer terminal with a datapad. Proceed further and you will come across another computer terminal with datapad.
Datapad no. 4
Use the elevator to reach the top of the CELL System-X Harvesting Facility. When you exit the elevator turn left and you will see computer terminal with datapad no. 4.