4 more BIOS dumps for mc1502, one of them includes hard disk support -- http://zx.pk.ru/showpost.php?p=582719&postcount=81

Schematic for that hard disk controller (uses i82064) and the machine itself (not sure which hw revision), in OrCAD format -- http://zx.pk.ru/showpost.php?p=583031&postcount=87

I will add the dumps to MESS; not sure how to convert OrCAD files to svg or something though.