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soci
Registered: Sep 2003
Posts: 479 |
Formatting disks with faults
Is there a disk formatting tool for 1541 which is able to detect a small faulty location and then it can lay out the sectors so that the fault ends up somewhere in a gap?
I have lots of slightly faulty disks which I don't want to throw out just because there's a small fault on one of the tracks. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
You can always tag the faulty blocks as claimed in the BAM. New files will not occupy that space then. Doing a verify operation will however undo your BAM-trickery. |
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chatGPZ
Registered: Dec 2001
Posts: 11359 |
thats not a good idea, it would mean modifying the gap lengths, which in turn increases the chance that writing to the disk will no more work.
other than that, you can use the formatter from "the final replay" - it will mark bad sectors as used in the BAM. |
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soci
Registered: Sep 2003
Posts: 479 |
BAM marking is ok for files, but I want to write D64 images, as file loader demos are long gone.
You're partly right about problems with changing gap lengths. The header gap is always a fixed number of bytes, so the first write will undo any gap size change there. But the inter-sector gap can be safely increased. (see Format II by LFT)
There's no need to change the gap sizes at all. I was only thinking about moving the tail gap to the faulty location, which would be the most compatible option.
This would be done by writing the first sector right after the fault. The last sector would be hopefully finished before the fault comes around again.
Achieving this would be a world first then? |
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Krill
Registered: Apr 2002
Posts: 2969 |
soci: I am not aware of such a tool. But it should be possible if, as you suggested, there's only one error on the track AND it's not bigger than a tail gap on that track.
Quoting socibut I want to write D64 images, as file loader demos are long gone. Not true, many demos still use files with the standard format. But yes, you'd not file-copy demos to your faulty disks and risk skewed timing and strange bugs. |
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chatGPZ
Registered: Dec 2001
Posts: 11359 |
one big problem with this idea is that you dont have a reference point (index signal) so you could shift the track to a defined offset... it'd be tricky to make a formatter that does this (in reasonable time anyway) |
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ThunderBlade
Registered: Jan 2002
Posts: 77 |
What is the point of this? Keep using disks that are broken? I'm sure there are enough working disks left - especially with the ton of 1541 Ultimate's being sold, I bet many are ready to donate a few, if needed. :) |
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soci
Registered: Sep 2003
Posts: 479 |
Sure, but if I throw them away and get new ones then where's the challenge? ;)
Groepaz: The fault location can be the reference point. Using absolute positioning (e.g with an 1571) would only complicate it.
I think I'll give it a try, this sounds like a fun project ;) |
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soci
Registered: Sep 2003
Posts: 479 |
Seems to work. But still a lot to trash ;) |
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ThunderBlade
Registered: Jan 2002
Posts: 77 |
A cool challenge in any case. |
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soci
Registered: Sep 2003
Posts: 479 |
Less trash now that I've fixed up the algorithm and the weak area detection.
This is what came out of this:
21st Century Floppy Disk Formatter V0.1
Probably not perfect, but it also depends on the disks too. Sometimes only soap and water helps ;) |
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