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Write back dumped disk

Posted: Sat Aug 08, 2020 9:34 pm
by pieroandreini
Thanks to ZrX and his tool, and Mark Odgen disktools ( I was able to decode several 8 "floppies dump written with a sector byte of 288 bytes. Now I would like to be able to write them back to floppy and being impossible to do it with a PC I would like to do it with kryoflux but even it doesn't seem to be possible at the moment.
How could I do?

Re: Write back dumped disk

Posted: Mon Aug 10, 2020 3:19 am
by SomeGuy
Have you tried just writing the kryoflux stream dump back as-is? If the dump had minimal "noise" this may work. Otherwise you will have to at least decode to MFM and then back to Kryoflux stream files.

Re: Write back dumped disk

Posted: Mon Aug 10, 2020 2:57 pm
by pieroandreini
I tried but unluckily it want work... I done it with the following command:

dtc -w -Wi4 -we1 -f./Desktop/NEC_Aligned/mill_ok/track

Computer start booting than appear "LOAD ERROR 26"

Re: Write back dumped disk

Posted: Mon Aug 10, 2020 9:38 pm
by brightcaster
You have to fiddle with the -ww, -wt and -wb parameters as the default automatics of precompensation and bias are not coded for 8" drives I guess. But to be honest I have no idea what values to use for these drives...

You sometimes get better copies (at least on 5.25") with using -we2 (wipe).

You may use the wildewutz tool from the kryoflux download page. With this you can check the parameters with the mouse using a nice gui...


Re: Write back dumped disk

Posted: Tue Aug 11, 2020 8:04 pm
by pieroandreini
may I retrieve values for precompensation and bias somehow?
As an example may I read back written disk to understand which values are correct?

I tried wipe but the head goes until track 82 and I don't want to take the risk of damaging or misaligning the drive.

For sure I will try wildewutz tool.
Maybe somebody want to add 8" Texas Instruments DSDD, to the supported kryoflux systems?
I'm probably saying something stupid, but wouldn't it be possible to have a menu in which the various parameters are entered in order to create profiles?
I mean: the information on the attached image is not enough to create an ad hoc profile for read and wite such floppies?

Re: Write back dumped disk

Posted: Tue Aug 11, 2020 10:11 pm
by pieroandreini
Searching for some useful info I found this document: ... _Jun82.pdf
May I suppose to use precompensation for track 27 (or 26 if the first track is 0) ?

Re: Write back dumped disk

Posted: Tue Aug 11, 2020 10:53 pm
by pieroandreini
I tested wildewutz tool but I could see that unlike what happens on MacOS using command line DTC, writing is much slower and takes place in three different cycles. Although I have set Max Track 76, using -we2 (wipe) the head is slammed to track 82, and in this case, since the writing occurs in three phases, this happens three times

Re: Write back dumped disk

Posted: Sat Aug 15, 2020 11:38 pm
by SomeGuy
The track 82 issue is a long standing bug. The Kryoflux software ignores any maximum track setting so it can write its own ID track on track 82, and they won't change that behavior. The idea is it is supposed to prevent people from writing "fake" copy protected disks with the kryoflux.

Unfortunately that means if your drive only supports 77 tracks, the head may bounce back and overwrite data on one of the last tracks. If your drive can at least position a few tracks after that, then it might not overwrite data, even though it still hits the stop.

I have no idea about write precomp or bias. If you try reading your copy back in with the kryoflux and posting that here, perhaps it could give some idea where things are going wrong.

I have absolutely no idea if this will help, but I decoded the stream to MFM and then back to kryoflux stream file using the PCE tools. This cleans up any "noise" in the image, making it ideal for writing, but since the sectors are non-standard I can't tell if there were any problems. ... 4099365764

Re: Write back dumped disk

Posted: Tue Aug 18, 2020 1:04 pm
by pieroandreini
thank you @SomeGuy!

unfortunately I cant try because it give me this error in both my computers:

iMac:~ piero$ dtc -w -Wi4 -we1 -f./Downloads/mill_6th_read_converted/track
Image name: ./Downloads/mill_6th_read_converted/track
Image type: RAW
Image sides: 2
Image tracks: 77
libc++abi.dylib: terminating with uncaught exception of type std::length_error: vector
Abort trap: 6
iMac:~ piero$

This dump (the last) coul be really better than the other: ...

Which tool you used for "clean" the dump??

Re: Write back dumped disk

Posted: Wed Aug 19, 2020 2:29 am
by SomeGuy
Oddly my conversion worked fine on my older DTC, but not on the newer one. One of the tools I was using has known bugs.

I've reconverted it and posted it here: ... 9103086620

(at least for me, this one now writes using DTC 3.0)

I used the PCE emulator tools (PFI/PRI/PSI) to convert to an MFM decoded text file, and then back to a kryoflux file. The latest version still has some odd bug that gets some speed related value wrong, so I have to then open and resave what it creates using the HxC software. That has worked for me before with IBM PC disk images.

Looking at your commandline, you need to use image type 0 (preservation stream file), and you might need to add the -v360 option.

But again, I don't really know if this will write something that the machine will actually be happy with.