PDA



The PDA (Personal digital assistant) is one of Doom 3's most useful items. It acts as a media player, email reader and access key for restricted areas.

Besides the player's personal PDA, other PDAs can be picked up and scanned to read helpful hints (including backstory, hints to monster types ahead, and combination codes for lockers).

PDAs you are not supposed to have are attributed to Duncan Mathews, and contain the contents of his pda.

Secrets
The last level contains the id PDA which contains special messages from the developers of the game. Immediately before entering the room with the Cyberdemon, there is a button marked with the id Software logo. Pressing this opens a door to a secret room containing the PDA.