12-19-2013, 02:14 PM
Thanks for the info. I do not believe in the "no flux area" theory. There are flux transitions always returned by the drives. Some drives return a pretty reliable version of the magnetic data, and some are so-so. Using a logic analyzer, you can record the flux transitions and compare them with what the drives return. In the case of the Panasonic JU-256A216P drives, the flux transitions returned equal the time that passes as the disk spins, even if its many milliseconds long. Typically, the time is broken into maximum blocks of around 25,000us. So, even though there is a portion of the disk where there were no deliberate flux transitions written, the magnetic data is still changing due to the magnetic field of adjacent tracks. The AGC is cranked up extremely high when this occurs and the data is clocked correctly. Some Epson drives return short-long-short-long bit cell periods during these times.
For SuperCard Pro, it does not matter as these protections are duplicated without needing to do anything but write the data back as it is read. Although I have not tried Turrican, I have reproduced what you call "no flux areas" manually without any issues and duplicated those by reading and re-writing the data using the SuperCard Pro analyzer. I will see if I can find an original Turrican just to verify it works.
For SuperCard Pro, it does not matter as these protections are duplicated without needing to do anything but write the data back as it is read. Although I have not tried Turrican, I have reproduced what you call "no flux areas" manually without any issues and duplicated those by reading and re-writing the data using the SuperCard Pro analyzer. I will see if I can find an original Turrican just to verify it works.