Doubtful if you can make your own codes brother!<br />However you can edit existing hex codes using Snx editor. Load the eeprom hex file and just add your own valid ppua and mk1. The mk1 goes (opposite 1/9) and monthly codes go opposite 4/C and 5/D. Set expirey date to suit and PBM then save file for use. This editing will only be accepted by AU hex's such as Keylog, Threat and Monkey. The hex files usually come in either 2 or 3 parts. The eep.hex, the pic.hex and sometimes the loader.hex. The loader is not usually required depending on what progger you use. Before running Cardmaster, make sure your progger is connected to one of your comms ports with serial lead. Put card in progger. Run the program and select correct comms port. Under Cardtype select Goldcard. Where it says File to Eeprom, load in the eep.hex file then Write Eeprom. Where it says File to Pic load in your Pic.hex file then Write Pic. (Names vary but usualy contain eep or pic somewhere in the title.) Thats it. Good luck, hope this helps.