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5.25 floppies image profile

Posted: Wed Jan 13, 2021 7:37 pm
by beppe
hi everyone, I am new with the Kyroflux board and I am not expert about retrocomputers.
I am trying to read some 5.25 floppies. I don't know what kind of Image Profile should I choose. Could you help me please? Thanks a lot.
Giuseppe Ferrari from Venezia, Italy

Re: 5.25 floppies image profile

Posted: Wed Jan 13, 2021 10:35 pm
by brightcaster
Nobody can tell that if you don't provide some information about the computer system they are made with! Just being 5.25 inch in size it could be everything from the profiles list...

David

Re: 5.25 floppies image profile

Posted: Thu Jan 14, 2021 4:32 pm
by beppe
hi David, thank you very much for your answer. Unfortunately I have no information about the computer system they are made with.. So I should perform many profiles and then test everyone?
thanks again

Re: 5.25 floppies image profile

Posted: Thu Jan 14, 2021 4:53 pm
by SomeGuy
In this case, it would be a good bet to start with a Preservation Stream File. That just records all of the raw signal from the drive. You can feed it back to the Kryoflux software or other tools later to decode a usable disk image using one of the other profiles.

The nice thing about this is you don't have to keep the disk spinning and wearing out experimenting with the decoding profile.

There are still a few things you ideally should know about the disk before hand. Specifically, is this a high density or low density 5.25" disk? What TPI was the disk written with (48TPI, 96TPI, 100TPI, may not match the vendor's label)? Was this disk used as a "flippy" disk (common on Apple II and C64 systems)? The wrong setting on these means you might not get everything.

Another nice thing about preservation stream dumps is that if you really can't figure out how to set up a decoding profile for the disk content then you can post the stream dump for others to look at, and usually it will contain enough clues to get something going.

Now if one of the above settings turned out to be wrong or if there was damage on the disk, that would have to be addressed and the disk would need to be redumped.

Hopefully that will get you started. Given all the cazy formats out there, it is not always simple.

Re: 5.25 floppies image profile

Posted: Fri Jan 15, 2021 6:59 pm
by beppe
Thanks a lot SomeGuy for your answer.
So now I tried to dump a floppy with preservation Stream profile.
Here you find the raw files and the log:
https://wetransfer.com/downloads/cb4cd3 ... 904/c88ce8
Could you please help me to figure out what is my format?
Thank you very much again!
beppe

Re: 5.25 floppies image profile

Posted: Sat Jan 16, 2021 4:39 pm
by brightcaster
This decodes fine to mfm sector image with 40 tracks, 10 sectors , 512 byte. But the last 6 tracks on side 2 are missing or not formatted! And the floppy looks as beeing almost empty (not just formatted but filled with hex 6D). I don't have any clue about the filesystem at all!

David

Re: 5.25 floppies image profile

Posted: Sun Jan 17, 2021 2:54 pm
by beppe
Thank you David, do you think it could be helpful to see other dumps? I have some other floppies from the same origin and I can try with them. Another question: Another question: from what I attached last time can you tell if the floppy drive is working correctly? It's not mine, I got it for this occasion, it's not related to the floppies and I can't say for sure if it's fully functional.
Thanks a lot for your precious help.
beppe

Re: 5.25 floppies image profile

Posted: Sun Jan 17, 2021 7:18 pm
by brightcaster
Yes, it would be nice to see a dump with some data on it and not just an empty disk. It would also be interesting to see if the last tracks are unformatted per design (on each floppy) or or only an error on that particular floppy.

The drive seems to be fine. There are no errors in the dump (at least until track 74 on side 2)...

David

Re: 5.25 floppies image profile

Posted: Tue Jan 19, 2021 4:46 pm
by SomeGuy
brightcaster wrote: Sat Jan 16, 2021 4:39 pm This decodes fine to mfm sector image with 40 tracks, 10 sectors , 512 byte. But the last 6 tracks on side 2 are missing or not formatted!
Actually, they are formatted and contain the same blank data. They appear to decode OK with the PCE tools and the Kryoflux software. There is just some noise or something on those tracks that throws off HxC. It is an odd thing to run in to, but I have seen that a couple of times before.

Re: 5.25 floppies image profile

Posted: Tue Jan 19, 2021 6:33 pm
by brightcaster
Aahrg! Yes it looks as if HxC is bad in this case and the floppy is fine! Never saw this behavior before

So now we know that it's standard mfm encoding, 400k in size, organized double-sided with 40 cylinders, 10 sectors, 512 byte. And its not MS-DOS, CPM or UNIX (according to whats written on it). So there are only some typewriters, music synthesizer, measuring instrument or CNC machines with a proprietary file system left I guess.

David