Mouse and SAM DAC work great! Thank you very much!
Now let's go back to the hard disk support
There are some images from different people available on internet. The best example would be a collection of demos:http://sam.speccy.cz/al-software/sc-demos_collection_2014-11_atomlite.7z
You can try it in SimCoupe 1.1 alpha. It starts to the fullscreen menu. You can select the demo using mouse or by pressing only one key. To use HDD you need to insert B-DOS disk D1 (as disk1 - HDD has to be connected as D2) or use modified ROM (AL-BOOT ROM), which can start from HDD if present (then HDD can be connected as D1 or D2, I think).
There's my very old demo on this image, but modified by someone. I haven't named it "Samples 4 SAMCon"
This is 3-disk demo and you had to change disks when prompted. Someone modified it for HDD and now it changes disks by itself. How? It is not magic
Just simple BASIC command: ' DPOKE DVAR 25,(DPEEK DVAR 25)+1 '. DVAR 25 is a DOS variable containing the number of the current partition. It sets the next partition as current. The demo simply must be saved in consecutive records and that's it.
HDD support would be very useful, but you have to decide for yourself whether it is worth.