Extracting non-standard DOS images

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Extracting non-standard DOS images

Post by Darkstar »


Apparently, I did format some disks back then with a nonstandard sector layout (i.e. 1.2" HD disks with 16 instead of 15 sectors per track). I was amazed that KryoFlux did dump them correctly as 1.310.720 bytes file (but as I thought about it that is expected).

However, I have not yet found any tool that can open/mount these images to extract the files inside. The TotalCommander plugin just shows an empty disk, and DosBox's imgmount tool apparently mounts them as standard 1.2mb images too.

Is there any tool that can read/extract these files?

Also, I have some disks that were created by some program called "Central Point Backup" which was really popular back in the day. It also uses a non-standard disk format which probably works the same (i.e. more sectors/track but I can't tell for sure because I didn't dump a disk yet)
Since CPBackup is a real bitch to set up on anything more modern than a 486DX33, it would be really interesting to know if there's any tool available to extract data from CPBackup images. I googled a bit but didn't find anything useful. Anyone have any pointers?


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Re: Extracting non-standard DOS images

Post by mr.vince »

Amazing, huh? KryoFlux will detect what we call "generic MFM" and decode data accordingly. Reading a filesystem from this sector dump must be done by additional tools. I know that some decoders are available in source format. And, if I remember correctly, MS DOS had the option to set drive parameters via config.sys. Maybe that's going to work in DOSBox... not sure.

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Re: Extracting non-standard DOS images

Post by Malvineous »

It might work in DOSBox if you have a real DOS disk you can boot with the BOOT command (after mounting the image with IMGMOUNT) as then the real DOS would take over disk access instead.

Of course this is something I'm sure the DOSBox people would be interested in implementing, especially if you could give them some sample images to work with.

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Re: Extracting non-standard DOS images

Post by porchy »

I find MagicISO opens all my IMG files without problem where as most of the other program claiming to open "any" image file failed.

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