Comments on: Virtualization Challenge IV – QNX 1.2

By: Rob

Rob — Sat, 08 May 2021 23:47:19 +0000

In reply to tenox.

You can try this command on the re-dump if your using a 1.2MB drive:

dtc -f”qnx_boot” -i0 -k2 -i4 -d1

And to test write it back to a new floppy disk with:
dtc -w -wi0 -f”qnx_boot.00.0.raw” -d1

You can also output the log to a file with >
path\to\output.log and use -l8 for a format log view and output

By: tenox

tenox — Mon, 03 May 2021 11:12:44 +0000

In reply to Rob.

You previously said “DTC will complain when a packet is missing” now I need a flag to turn it on?

I think maybe send me the exact command for DTC I should try?

By: Rob

Rob — Fri, 30 Apr 2021 09:24:53 +0000

In reply to tenox. If you inspect the raw files they have errors. Depends what log level you have setup for dumping you will see things or not. Try writing the boot disk back to a blank floppy with your KF and you will see :)

By: tenox

tenox — Fri, 30 Apr 2021 09:22:16 +0000

In reply to Rob. I had no errors when dumping it.

By: Rob

Rob — Wed, 28 Apr 2021 13:58:52 +0000

I’m sorry I don’t know enough about the internals of the KF device to answer that question . The Kryoflux Team mentioned the following:

“Each USB packet is serialised and DTC will complain when a packet is missing and mark the read as bad. So this dump must have taken ages with a dozen error messages per track.”

By: tenox

tenox — Wed, 28 Apr 2021 12:55:59 +0000

In reply to Rob. I still don't understand how USB transfer could affect data. Is Kryoflux sending analog audio signal over it? But even then USB is a digital protocol with error correction. If there were issues with data transfer why wouldn't KF software tell right away that there was an issue, instead of writing incorrect data to an image. This doesn't make any sense.

By: Rob

Rob — Tue, 27 Apr 2021 08:57:28 +0000

From what we’ve seen with the guys over at KF is the dumps are bad. There is no doubt here. Emulation works differently to real hardware. Its probable (as we have seen) that it allows you to boot and “apparently works” but when you do something that needs the area of the image/disk that is damaged then QNX will bomb out because its missing data there. There is data missing from the tracks due to the dumping problem with the USB.

If you have access to the original floppuies test it. Clean gently the floppies with a lint free cloth and with a mixture of Isopropyl alcohol/ distilled water. Clean floppy drive heads with alcohol and Q-tips. Use a different USB port or remove the USB hub and redump. Let’s see the outcome.

By: tenox

tenox — Mon, 26 Apr 2021 11:35:52 +0000

In reply to Rob.

Okay here is something that I don’t get. USB is a digital protocol. Packets either go through or don’t. USB itself has error checking and correction. It can’t damage data unless the data sent was already “bad”. I would rather assume that either the floppy disk medium, floppy drive or fdd cable has an issue, not USB. Finally these images were used to boot in an emulator so digitally they are correct. If the images were “bad” you won’t be able to boot and use them would you?

By: Rob

Rob — Mon, 26 Apr 2021 10:57:48 +0000

I’ve quickly checked the others and they have simular USB errors. I would recommend dumping again all 5 floppy disks (these images are bad), piping the output to a log file, checking the USB does not go through a hub and using a 48tpi drive if possible. Also set the density line for dumping to DD mode, e.g. -dd1.

By: tenox

tenox — Mon, 26 Apr 2021 09:45:50 +0000

In reply to Rob. Okay thats bit better. Thank you. Is this specific to one disk image or all disk images?