micko, AFAIK, the char-generator on the 1715/1715w is downloadable. It seems, the i8275 is not enough, you have to implement this part too. Another issue is a banked memory on the 1715W. All known SCP3 uses banked RAM as an E: RAM drive.

I have 3 different bootable 1715W SCP3 diskettes (and some hand-made non-bootable diskettes with CP/M software). All SCP3's sub-versions are different, but I haven't "full" SCP3 distributive.

http://www.leningrad.su/files/robotron_scp30.bin

It's a sector-by-sector image of the bootable SCP3 (2*80*5*1024).

AFAIK, Track=0 contains a second-stage bootloader which initializes hardware and loads rest of SCP3 into (banked?) memory.