All invalid tracks should be exported to an decoded format

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thomas
Posts: 2
Joined: Tue Jan 30, 2018 12:00 am

All invalid tracks should be exported to an decoded format

Post by thomas » Tue Jan 30, 2018 10:29 pm

I read a 3.5" floppy disk (HD, MFM, 80 tracks, original disk without copy protection) using the KryoFlux controller. The created image "disk.img" works perfectly (mounted in Virtual Box and accessed files).
All standard tracks 0-79 read in successfully. For track 80 a "<mismatch>, *N" was reported and tracks 81-83 where unformatted.
I was interested in what kind of data is stored in track 80 so I tried to read the content e.g. with an hex editor. The problem was that the tracks 80-83 were not stored in the "disk.img" (maybe because of automatic image sizing) so no data was there to inspect. The parameter -os -oe (output image start/end track) did not solve the problem. Also the stream files cannot be used directly to search for an disk content.

Is there an easy way (except with programming) to access the content e.g. from track 80 as if it had been read by an standard floppy disk controller even if the track is invalid or contains garbage?

[Log file]

Code: Select all

01d4c96a: motor=1
01d4c97e: side=1
01d4c993: track=79
01d4c9a7: stream=1
01d4ce93: stream=0
79.1    : frev: 76783, drift: 0.616 us, tfer: 369001 B/s, rpm: 300.801
79.1    : band: 1.971 us, 3.009 us, 4.027 us
79.1    : base: 1.003 us [99.287%], band: 1.971 us, 3.009 us, 4.027 us
79.1    : MFM: OK, trk: 079, sec: 18
01d4d087: motor=1
01d4d09b: side=0
01d4d0b0: track=80
01d4d0f6: stream=1
01d4d5ba: stream=0
80.0    : frev: 78744, drift: 0.433 us, tfer: 376838 B/s, rpm: 300.800
80.0    : band: 2.001 us, 3.007 us
80.0    : base: 1.002 us [66.509%], band: 2.001 us, 3.007 us
80.0    : MFM: <mismatch>, *N

ZrX
Posts: 468
Joined: Tue Dec 06, 2011 9:09 pm

Re: All invalid tracks should be exported to an decoded format

Post by ZrX » Tue Jan 30, 2018 11:00 pm

A first unused track at the end of many disks contain a so-called duplicator info sector that holds fe. The manufacturer name of the disk, info about used protection, etc.

On some disks it's a single FM sector, others with just data on plain unencoded bits. It varies.

thomas
Posts: 2
Joined: Tue Jan 30, 2018 12:00 am

Re: All invalid tracks should be exported to an decoded format

Post by thomas » Tue Jan 30, 2018 11:15 pm

ZrX wrote:
Tue Jan 30, 2018 11:00 pm
A first unused track at the end of many disks contain a so-called duplicator info sector that holds fe. The manufacturer name of the disk, info about used protection, etc.

On some disks it's a single FM sector, others with just data on plain unencoded bits. It varies.
Thanks for the info.
I also use the -i3 option (FM sector image) with -s80 -e80 but the image file remains empty.
The dtc reports the message "FM: <unformatted>".

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mr.vince
Posts: 2086
Joined: Tue Oct 05, 2010 5:48 pm

Re: All invalid tracks should be exported to an decoded format

Post by mr.vince » Wed Jan 31, 2018 10:43 am

What shall KF put into the image file, if decoding fails? If it does not fit the decoding scheme, there's not much that can be done (except for using a container that can store such data, e.g. Stream).

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IFW
Posts: 3077
Joined: Mon Nov 08, 2010 2:42 pm

Re: All invalid tracks should be exported to an decoded format

Post by IFW » Wed Jan 31, 2018 2:01 pm

You can try changing the sector size, but if it's duplicator info that won't help as most of them are deliberately non-standard to prevent accidental reading by the target system.

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