Problem reading side 1 of a 360k PC disk

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NRS
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Joined: Mon May 06, 2013 8:32 pm

Problem reading side 1 of a 360k PC disk

Post by NRS »

I am trying to read two 5.25" 360K PC disks from a PC version of King's Quest II that was sold in Radio Shack stores and therefore has Tandy, rather than Sierra, disk labels. (The licensing agreement went so far as to display "Licensed to Tandy" on the game's title screen.) Under Kryoflux, the second side on both disks is completely unreadable, either not recognizing any sectors at all, or yielding only bad sectors. This happens only with these two particular disks, no problem with any other PC disks, Sierra or otherwise, 160k/320k/360k/1.2M or otherwise. And yet both disks read perfectly under DOS even with the exact same drive.

What might be the cause? I can attach track 0 stream files if desired.

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IFW
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Re: Problem reading side 1 of a 360k PC disk

Post by IFW »

Yes, please, would be interesting to see them, but at least the first 3 tracks of both sides.

NRS
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Re: Problem reading side 1 of a 360k PC disk

Post by NRS »

Here you are.
Attachments
kq2tandy_disk1.7z
King's Quest II for Tandy 1000 - tracks 0..5
(1.15 MiB) Downloaded 124 times

NRS
Posts: 27
Joined: Mon May 06, 2013 8:32 pm

Re: Problem reading side 1 of a 360k PC disk

Post by NRS »

Here are also pictures for proof of authenticity.
box.jpg
box.jpg (87.7 KiB) Viewed 2019 times
label.jpg
label.jpg (68 KiB) Viewed 2019 times
disks.jpg
disks.jpg (169.04 KiB) Viewed 2019 times

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IFW
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Re: Problem reading side 1 of a 360k PC disk

Post by IFW »

Side 1 is unreadable; take a look at the picture.
The 4us band has random noise anything ranging from 0 to 4 us...
Clean the drive head and/or the disk; it is also possible that the head is slightly misaligned.
You should not see random noise (apart from a very narrow band where the track gap is) once the disk/head is clean and the head is correctly aligned.
Alternatively, try to replace the floppy cable and/or use a different drive and/or PSU. Check there is nothing emitting electrical noise nearby (cordless phones, mobiles, speakers, some pc PSUs), correct grounding etc.

There is simply no way to read side 1 correctly when all that you get is random noise (does not matter whether it's KryoFlux or anything else), so either you are not actually reading it, or something is different in the setup if/when it works.
Attachments
bad.PNG
bad.PNG (79.14 KiB) Viewed 1990 times

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mr.vince
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Re: Problem reading side 1 of a 360k PC disk

Post by mr.vince »

Is the drive in an enclosure? If not... Is the PSU near the drive?

NRS
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Joined: Mon May 06, 2013 8:32 pm

Re: Problem reading side 1 of a 360k PC disk

Post by NRS »

I now managed to read both disks using DTC.exe directly. Previously I only used the GUI.

Side 1 failed to read, as before, with -i4 at default settings, but reads perfectly if I add the option -dd1. No other 360K disk I have tried needs that option to be read properly. Strange, isn't it?

Or is that something that I should have known all along? If so, why did every other 360k disk work without it?

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IFW
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Re: Problem reading side 1 of a 360k PC disk

Post by IFW »

Sounds like if side 1 was (re?)written with different coercivity...
Definitely not normal, so no worries :)

NRS
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Joined: Mon May 06, 2013 8:32 pm

Re: Problem reading side 1 of a 360k PC disk

Post by NRS »

Well, they do show up as "green" and not "modified" when viewing the stream files produced from the command line within the UI, so I guess it was then written at the plant incorrectly. Apparently normal PC floppy controllers don't care.

I just noticed though that I also need to specify -dd1 if I want to read Apple II disks with this drive (NEC FD1157C). It might be a good idea to add this option to the GUI, possibly in the "advanced" tab. (Or is it already there and I just don't find it again? :))

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IFW
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Re: Problem reading side 1 of a 360k PC disk

Post by IFW »

Rest assured the controllers would care (nothing can interpret noise coming from the drive instead of data...), unless you have that line pulled accidentally when connected to a PC :)

I asked our GUI expert to comment on the second part.

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