Writing BBC ADFS discs

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rolopolo
Posts: 6
Joined: Wed Jun 09, 2021 3:44 pm

Writing BBC ADFS discs

Post by rolopolo »

Hello all, I have had a look around and cannot see quite what I need to solve this problem.

In the reverse of the norm I have a KF to write discs as I like to use real hardware.

Seem to be getting on ok with Atari 8 disks, MFM and FM. My real sticking point seems to be The BBC micro and 640K ADFS on 5 1/4 drives.

I have successfully written DFS 200K and 400K and 800K MFM disks for the x86 coprocessor. I just do not have any luck with 640K discs which for me are the most important.

My workflow is to create a KF stream from the image files and then write these with pre erase with the KF. Doing this I can get green on every sector using the GUI when I read a written image back. The image I believe correct as I compare the source disk image I made the KF stream with to the read back one. Identical, all seems very good. The images are readable with PC based ADFS image readers and contain valid files.

The problem is, a real BBC floppy will not read the written back disc at all. Just a disc error.

Any ideas good people.
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mr.vince
Posts: 2201
Joined: Tue Oct 05, 2010 5:48 pm

Re: Writing BBC ADFS discs

Post by mr.vince »

Might be the drive in your BBC or the floppy drive you use to write disks are misaligned. This would explain why you can read the disk with the drive you used for writing. Can you check alignment?
rolopolo
Posts: 6
Joined: Wed Jun 09, 2021 3:44 pm

Re: Writing BBC ADFS discs

Post by rolopolo »

Thank you for getting back to me. I now have another drive to use with KF. This is the same Chinon FR506 drive as used in the BBC setup I have. What must be said though is that it has fewer jumpers so that is not quite the ideal. I don't really have a way to test alignment in a definitive way. I think all I can add to possibly dismiss alignment is that I can write 800K MFM BBC discs with the KF without I problem, these are 1K sector, 5 sector per track MFM. I wrote quite a few of these as this the odd format for The BBC using streams created with the HxCFloppy emulator, the same as for the 640K BBC ADFS discs.


I have to two refurbished drives attached to The BBC micro paired together in a case and they are identical. Neither will read the KF output discs. They came from the same source as refurbished. They looked like new, is it possible the vendor has realigned them?
rolopolo
Posts: 6
Joined: Wed Jun 09, 2021 3:44 pm

Re: Writing BBC ADFS discs

Post by rolopolo »

Following up one point is that the real ADFS discs created on a BBC seem to have both sides marked with side 0, so in the GUI the upper side of the disc is always marked with and S. The discs created with the floppy emulator are 'correct' with 0 or 1 as appropriate. I have made single side ADFS images though with just side 0 and they still fail.
brightcaster
Posts: 415
Joined: Fri Nov 08, 2013 10:48 pm

Re: Writing BBC ADFS discs

Post by brightcaster »

Have you tried reading the "real" ADFS discs with the emulator? Some sources on google say that a special adfs-rom was needed, otherwise you could only format a floppy in a 2 head drive as two separate logical drives with DFS, which would show up with physical side 1 as beeing logical side 0 of another drive...

I guess the problem is on the BBC micro side as the floppy controller should set correct side IDs!

David
rolopolo
Posts: 6
Joined: Wed Jun 09, 2021 3:44 pm

Re: Writing BBC ADFS discs

Post by rolopolo »

I think I can let the KF off the hook, I have always be sure that was ok. I have rerun the workflow of creating a blank 640K AFDS image using the HxC Emulator. As I had tried before one I used the create image rather than start with a pre-existing one. This worked the first time I tried it but but rather oddly did no read back with the KF using my default setup for MFM BBC discs. The real BBC could however verify the disk was readable, well I had problems reading the upper side near the centre. However using version 2.5.6.9 these blank disk images can be read using the KF with my ADFS preset and verify on the real BBC (with the same read failures on the upper side near the centre). I had read in forums that the blank settings were incorrect in the release version of HxC but correct in the version mentioned above. These all seems to point at HxC being the problem. The only issue for my setup seems to be that the upper side always fails to verify near the centre, I have two real BBC drives and two KF writing drives, all seem to cause the same errors on the real BBC near the end of the upper side. Of course the blank images have no filling system structures so cannot read or write files for further testing.

Thank you for looking in to this and of course writing is not a key feature and offered as a nice thing rather than as the aim of the product.

I turned to the KF as I went through a number of PC mother boards, one had leaked it's caps while in storage, one only claimed to support one drive and failed to work with the recommended BBC Micro tools and the third is just plain too slow to function with the software.

Thanks for the great product and your support.
brightcaster
Posts: 415
Joined: Fri Nov 08, 2013 10:48 pm

Re: Writing BBC ADFS discs

Post by brightcaster »

That could be a dirty head on the real BBC. It tends to read the inner tracks poorly at first...
David
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