Captured in KiCad by Stewart Orchard 2015-2019
Original design by Dragon Data Ltd circa 1982
The published Dragon schematics do not appear to include MKII versions, which can be a problem for repairs as there are differences in the memory configuration, the video circuit and logic gate pin numbers. I captured this information around the year 1998 with reference to the existing ISS2 schematics, a multimeter and a real MKII ISS6 main board, and have finally got round to recording it as a KiCad project.
Much as I would like to think that I've got this 100% correct, there is always the chance that there are mistakes and omissions. I would recommend checking that the information is accurate before using this schematic for anything potentially expensive.