SuperCard Pro Flux Image format (.scp)
This is not related to WD1772 FDC! This is related to the FD Drive and not FD Controller
And no, no data comes from the read data line Smile
This is the magic of this protection: as I said the read channel is in fact getting lots of transitions and therefore the ACG is kept at low amplification because it receives all these transitions but ... nothing is going out ...
If you look at the datasheets I have mentioned you will see that when transitions are getting closer the data bits detected are shifted. This protection "over-abuse" this behavior to the point that nothing comes out from the read channel (you can think of it as being filtered).
Quote:But like I said, I have deliberately tried ultra short flux transitions and there is no case that I can create where there is a NRZ state like you describe.
I do not understand what you mean?
As I said the write channel does not filter anything. So if your device is capable of "pulsing" the write data line at relatively high frequency you should be able to reproduce the protection. If you have a scope (unfortunately I dont) and Turrican you should be able to see what I mean.
Note that I got this information partially from Istvan but I have not been able to taste it because this would require a scope or Logic analyzer.

Quote:You have to remember that I don't ever look at decoded data, only flux level data. With the Amiga copier (SuperCard Ami) I also never looked at decoded data, only the raw MFM data stream. So, I never deal with sectors and headers and such, just flux transitions and determining the physical location of where the head writing was turned off.
This is quite interesting information. I now have to think about it to make sure this is always feasible with Atari protections. But great idea Cool

Messages In This Thread
SuperCard Pro Flux Image format (.scp) - by admin - 11-01-2013, 05:54 PM
RE: SuperCard Pro Flux Image format (.scp) - by DrCoolZic - 12-20-2013, 10:02 AM

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