Each extension modul consits of 4 words in the memory space. The first word (word with the highest address) is splitted in 4 parts (bytewise).\\
The first byte (beginning from the lsb) is the global status byte. \\
The second byte is the custom status byte. \\
The third is the global control byte. \\
The last is the custom control byte. \\
The other 3 words have functionality dependent on the extension modul. They can be readable/writeable. In some cases reading from one word will read a different register as the register that is written.

remark: maybe more words will be combined for one extension modul if necassery. Maybe 2 extension blocks are used for the same extension modul.got