Alain,
entering trees is not possible anymore since the Diablo release. It worked only for the Super Conny, Forte A/B and Super Forte A/B/C. Since then you can only enter single lines. However, at least for the Diablo it seems that even this one is not working correctly (please refer to this posting here).

With "read and write" to the Novag RAM I meant the possibility to get the opening book loaded into the PC modify it there and send the modified opening book file back to the Novag chesscomputer. This was possible in the 1st release of the interface as far as I understand it. I am sure that there is a protocol for this but as I never had this software I cannot give any further info, sorry