donQ

Hi, I just got a GBSat 2CI 20 to replace a Hyundai 800 CI, and was just using seca before, but as the GBSat is flashed for six providers decided to make a fun card. After a few attempts and a bit of experimentation I was successful, using a mix of files. I noted what I did for future use, but I now want to understand more about what I'm doing.
My main questions are what does the flash, eeprom internal and external files contain? Some 6 in 1 files for example don't have all three and have different names, so I had to work out which was which. I really want to know about these so I can maybe tweak and do other things myself to suit my receiver.
I use Cardwriter and a VXMulti prog.
Thanks for any help that can be given.