How to dump IBM HD 5.25" Disks?

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rcade
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How to dump IBM HD 5.25" Disks?

Post by rcade » Fri Feb 02, 2018 2:01 am

I've tried the normal things and have searched around a bit on the forum, but I'm at a loss here.

The disks work in a regular PC drive, and I'm imaging with a 1.2MB HD 5.25" floppy drive (Panasonic). I can read C64/Atari/Apple just fine with -dd1, so I figured -dd0 would read HD disks, but no luck so far.

dtc -p -ftest_ -i -ftest.img -i4 -k1 -d1 -dd0

Results in:
00.0 : frev: 64671, drift: 0.583 us, tfer: 370124 B/s, rpm: 360.577
00.0 : band: 2.411 us, 3.618 us, 4.828 us
00.0 : base: 0.904 us [52.787%], band: 3.618 us
00.0 : MFM: <unformatted>
00.1 : frev: 77039, drift: 0.524 us, tfer: 441158 B/s, rpm: 360.577
00.1 : band: 2.412 us, 3.615 us, 4.824 us
00.1 : base: 0.904 us [52.762%], band: 3.615 us
00.1 : MFM: <unformatted>

What am I missing? Bad DTC options?
-
Pete Rittwage
C64 Preservation Project
http://c64preservation.com

SomeGuy
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Re: How to dump IBM HD 5.25" Disks?

Post by SomeGuy » Fri Feb 02, 2018 4:39 am

If your 5.25" 1.2mb drive is configured for use with an IBM PC, then -dd0 is high density and -dd1 is low density. Kryoflux only refers to the density line TTL logic level. On an IBM PC: Logic low (0) sets high density Logic high (1) sets low density.

Why? Because some 5.25" drives from non IBM-PC compatible systems do things the exact opposite.

So just out of curiosity, what happens when you try to reverse this?

(This is driving me nuts because I keep getting this switched around in my head as I type this)

Kroflux can usually read low density disks when high density mode is set. Technically what this line does is alter the drive's analog amplifier AGC/filter behavior, so if the signal is still clear enough Kryoflux is happy.

Also, try adding -v360. Sometimes it needs that although you would think it would be able to figure that out.

ZrX
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Re: How to dump IBM HD 5.25" Disks?

Post by ZrX » Fri Feb 02, 2018 9:39 am

-v360 before the - i4 that is.

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IFW
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Re: How to dump IBM HD 5.25" Disks?

Post by IFW » Fri Feb 02, 2018 11:41 am

SomeGuy wrote:
Fri Feb 02, 2018 4:39 am
Also, try adding -v360. Sometimes it needs that although you would think it would be able to figure that out.
What KryoFlux knows is the current speed used by the drive while sampling the track.
This may or may not be the same RPM as the one used by the target platform of the disk being read.
The target platform RPM used by DTC is completely different; that is the RPM being used for actually decoding the track data (after conversion from current RPM to target RPM).
So if your target platform for the disk is using 360RPM for the format to be decoded and it's not the default for that specific format you should always set the -v360. DTC might be able to decode the track without that, but with a HD format it's very unlikely.

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IFW
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Re: How to dump IBM HD 5.25" Disks?

Post by IFW » Fri Feb 02, 2018 11:47 am

SomeGuy wrote:
Fri Feb 02, 2018 4:39 am
Kroflux can usually read low density disks when high density mode is set. Technically what this line does is alter the drive's analog amplifier AGC/filter behavior, so if the signal is still clear enough Kryoflux is happy.
Disks using reasonably short flux reversals (the majority of them, except for maybe Apple ones) work fine in either mode, the different AGC behaviour becomes a problem with custom formats that change well established flux encoding rules, e.g. overlong flux reversals that actually encode real data - instead of being used as a weak bit protection :lol:

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IFW
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Re: How to dump IBM HD 5.25" Disks?

Post by IFW » Fri Feb 02, 2018 11:50 am

Pete,

Might be a good idea to post a few tracks sampled with -dd0 vs -dd1

ZrX
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Re: How to dump IBM HD 5.25" Disks?

Post by ZrX » Fri Feb 02, 2018 1:43 pm


rcade
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Re: How to dump IBM HD 5.25" Disks?

Post by rcade » Fri Feb 02, 2018 4:45 pm

I'll post a couple tracks this weekend. I had no better luck with -v360 or -dd1 but it may be where it is in the command line? That confuses things a lot...

I occasionally have some C64 disks that read poorly unless I explicitly set -dd1, so it has some effect on my Panasonic.
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Pete Rittwage
C64 Preservation Project
http://c64preservation.com

rcade
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Joined: Mon Nov 21, 2011 5:21 pm

Re: How to dump IBM HD 5.25" Disks?

Post by rcade » Sat Feb 03, 2018 4:42 pm

-v360 before -i4 did it. At the end of the command line, does nothing. Why is the order important?
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Pete Rittwage
C64 Preservation Project
http://c64preservation.com

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IFW
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Re: How to dump IBM HD 5.25" Disks?

Post by IFW » Sat Feb 03, 2018 10:26 pm

Because format local (specific) parameters are valid from the beginning of the command line until the first guide format (-i), then the first parameter after the last guide format until the next guide format and so on.
The main reason for that was that some parameters have both format local as well as global meaning, and anything after the last guide format specification is considered as a global parameter.
In retrospect it seemed like a good idea at the time (so we wouldn't have different parameter names for the same parameter just local vs global), but it complicated things after all.
Now all tools, gui etc. expect this so if we break this we break compatibility with all of those...

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