I changed the Indus doubler so that it is ATR "compatible". It is still double density 256 byte sectors, but sector 1 now loads the actual code from sectors 4 through 7, avoiding the 128 byte limit issue on sectors 1 to 3. I haven't changed the verify after write code yet (it checks CRC and only compares the first byte repeatedly, instead of comparing the entire sector). Note only sectors 1, 4, 5, 6, 7 are used. The rest of the sectors are all zeroes and not used. Link to zip of the atr file, o