If you look at the link that gives you your switch settings
http://www.teamxecuter.com/index.php?name=Forums&file=viewtopic&t=16102
You will see that the first lot of settings relate to 256K banks- -Banks 1 to 8
The chip has 2Mb Memory and 8 x 256k = 2Mb
So you can select any of the 8 different 256k banks (or memory blocks) by setting the 4 switches as per the list
e.g - if you wanted to flash bank 3 with a 256k BIOS you would set the 4 dip switches to On Off On On (Switches numbered 1 to 4)
if you wanted to flash bank 6 with a 256k BIOS you would set the switches to Off On Off ON (switches numbered 1 to 4)
As most of the BIOS are around 1MB (X3), selecting a bank of 256k would not be enough - Cant get a gallon into a pint pot. So the list carries on to give the setting for 512K, 1Mb and 2Mb banks (or memory blocks)
SO- if you wanted a 1 MB bank to flash the latest X3 Bios you would have 2 choices (as the chip is capable of 2 Mb of storage)
Chioce 1 would be using banks 1 to 4 (4 x 256k = 1MB) which you would select by setting the switches to On On Off OFf
or Chioce 2 - Banks 5 to 8 by setting the switches to Off On Off Off.
You will notice from the table that no switch settings on that list are the same - They are all different to enable you to select different options.
Hope this helps
Its all in the forums m8.