Those are the Codes used in the PC Version (NOT the ArrangeMode) & Japanese Disc Version PS1

1. Lock Numbers

   0375 - Custody Room (The one with a dead guard and also the first save point. 
                   Don't forget to hit the switch on the wall first.) 
   
   8159 - Louge weaphon storage locker (The thrashed bar in the 2nd floor of the 
                   facility) 
   
   705037 - The room adjacent to the Louge (You need to  use a DDK here. Once 
                     you're inside you'll meet a researcher and use the 2 panel keys on the 
                     plaque behind the desk. The letters on panel keys, LEO & SOL, is 
                     actually the lock code. Try writing it on a piece of paper or on a 
                     calculator then read it upside down.) 
   
   5037 - Computer room (Opens the gas chamber room.) 
   
   1218 - Stabilizer design room (Use this code on the panel the get the upgrade 
                   parts for the shotgun.) 
   
   367204 - Forgot which room to use this one. (It is the room where you'll get the 
                     parts for the stabilizer and initializer.) 
   
   0367 & 0204 - Stabilizer & Initializer  Assembly Room (Use the first code in the 
                          computer terminal & the 2nd one in the thing that looks like a 
                          large vending machine in the corner.) 
   

   2) DDK Codes

   HEAD 
   NEWCOMER 
   LABORATORY 
   ENERGY 
   WATERWAY 
   STABILIZER 
   DOCTORKIRK 
   

   3) Registration Numbers

   Paul Baker - 46907
   
   Dr. Kirk   - 78814 
    
   

   4) Gas Combinations

   RED -defeats-> GREEN 
   BLUE -defeats-> ORANGE 
   GREEN -defeats-> PURPLE 
   
   (Use this in the gas chamber room. Sometimes you have to mix the gases to come up 
            with the right colors.)