Workflow to modify a standard floppy

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Oliver2018
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Joined: Fri Jan 25, 2019 10:38 pm

Workflow to modify a standard floppy

Post by Oliver2018 » Sun Jan 27, 2019 8:56 pm

For a better understanding of how DTC works: how is the exact procedure (DTC command parameters) to read/save a 1.44 DOS HD floppy disk into a file, then convert it to a 1474560 bytes sector image, and then write the modified 1474560 image back to the HD floppy disk?

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mr.vince
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Re: Workflow to modify a standard floppy

Post by mr.vince » Wed Jan 30, 2019 2:27 pm

Did you try yourself? What was the command line? What happened?

Oliver2018
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Joined: Fri Jan 25, 2019 10:38 pm

Re: Workflow to modify a standard floppy

Post by Oliver2018 » Thu Jan 31, 2019 1:17 am

In order to get familiar with DTC, I tried to create a 1.44 MB sector image from a 1.44MB DOS HDD 3.5" floppy with different settings without success.

1.44 MB DOS 80 Tracks, 2 Sides, 18 Sects, 512 bps

The last Image file (512bps sector dump has 9MB instead of 1.44MB).

reading
dtc -f%tdir%\3xxx -i0 -m2 -z2 -g2 -dd1 -l2 -s0 -e79 -n+Z=18 -k1

=>160 files are created with different sizes.

Convert
dtc -p -m1 -f%TDIR%\3xxx -i0 -f.\3xxx.img -i2 -g2 -z2 -g2 -dd1 -s0 -e79 -n+Z=18 -k1
=> File with 9MB is created instead of 1.44MB

ZrX
Posts: 575
Joined: Tue Dec 06, 2011 9:09 pm

Re: Workflow to modify a standard floppy

Post by ZrX » Thu Jan 31, 2019 3:21 pm

dtc -m1 -f%TDIR%\3xxx -i0 -f.\3xxx.img -i4 -e79 should work.

The manual has more examples.

Oliver2018
Posts: 6
Joined: Fri Jan 25, 2019 10:38 pm

Re: Workflow to modify a standard floppy

Post by Oliver2018 » Fri Feb 01, 2019 12:18 am

ZrX,
Thank you very much for your suggestion.

Here are the results:

1. Reading
dtc -f%tdir%\disk -i0 -m2 -z2 -g2 -dd1 -l2 -s0 -e79 -n+Z=18 -k1

2. Converting
dtc -m1 -f%TDIR%\disk -i0 -f.\disk.img -i4 -e79

=> switching from "-i2" to "-i4" as suggested reduces the file size from 9MB to 0MB (File Size 0 bytes)

Here are the last lines from the console output:

79.0 : frev: 36576, drift: 0.092 us, tfer: 242124 B/s, rpm: 360.034
79.0 : base: 2.000 us [0.000%], band: 7.249 us?
79.0 : MFM: <unformatted>
79.1 : frev: 47953, drift: 0.441 us, tfer: 274971 B/s, rpm: 360.041
79.1 : base: 1.798 us [91.665%], band: 2.692 us?, 4.065 us, 5.394 us?
79.1 : MFM: <unformatted>

SomeGuy
Posts: 237
Joined: Wed Feb 18, 2015 8:18 pm

Re: Workflow to modify a standard floppy

Post by SomeGuy » Fri Feb 01, 2019 5:15 am

On #1, Specifying sector parameters is irrelevant when dumping a stream file - it will always dump everything regardless of content. "-z2" and "-n+Z=18" should be on your converting command instead.

Also, for a high density disk in a typical drive you must specify logic line low, -dd0. Remember, the density line logic level is normally opposite of the density. The fact that you are showing 360RPM instead of 300 suggests you have a "Japanese Mode 3" compatible drive. With these drives, 360RPM is engaged by an intentional density hole/density line mismatch. You want 300RPM.

Oliver2018
Posts: 6
Joined: Fri Jan 25, 2019 10:38 pm

Re: Workflow to modify a standard floppy

Post by Oliver2018 » Sat Feb 02, 2019 2:31 am

Thank you very much!

That was it!

I used a 3-mode drive and changed it to 300rpm (via switch).

1. Read
dtc -f%tdir%\disk -v300 -m2 -g2 -dd0 -l2 -s0 -e79 -k1 -i0

The '-v300' had no effect :-(

There were some errors => but 160 file were created!

2. Convert
dtc -m1 -f%TDIR%\disk -i0 -f.\disk.img -i4

some lines from conversion process:

36.0 : frev: 75694, drift: 0.333 us, tfer: 432898 B/s, rpm: 360.034
36.0 : base: 1.000 us [99.684%], band: 1.973 us, 3.001 us, 4.000 us
36.0 : MFM: OK*, trk: 036, sec: 18, *H +12
36.1 : frev: 76267, drift: 0.533 us, tfer: 435778 B/s, rpm: 360.036
36.1 : base: 1.000 us [99.641%], band: 1.970 us, 3.001 us, 4.001 us
36.1 : MFM: OK*, trk: 036, sec: 18, *H +11
37.0 : frev: 75909, drift: 0.816 us, tfer: 433854 B/s, rpm: 360.041
37.0 : base: 1.000 us [99.644%], band: 1.973 us, 3.001 us, 4.004 us
37.0 : MFM: OK*, trk: 037, sec: 18, *H +15
37.1 : frev: 75816, drift: 0.824 us, tfer: 433375 B/s, rpm: 360.032
37.1 : base: 0.999 us [99.622%], band: 1.970 us, 2.998 us, 4.002 us
37.1 : MFM: OK*, trk: 037, sec: 18, *H +13

Could extract a single file form the sector image file with 1454080 bytes.

This file ("Setup.exe") seems to be ok! It starts without errors.

I will now try to write the image back to another diskette.

Oliver2018
Posts: 6
Joined: Fri Jan 25, 2019 10:38 pm

Re: Workflow to modify a standard floppy

Post by Oliver2018 » Wed Feb 06, 2019 1:28 am

I understood that it is not possible to write the modified 1474560 sector image back to the HD floppy disk because dtc.exe does not provide the Image type (-i4) in write mode.

Is this correct?

SomeGuy
Posts: 237
Joined: Wed Feb 18, 2015 8:18 pm

Re: Workflow to modify a standard floppy

Post by SomeGuy » Wed Feb 06, 2019 1:53 am

The -v300 parameter does not change physical drive speed (or different hardware filters the drive may use at different speeds), that only affects decoding. If the data rate on the disk is faster/slower than what the Kryoflux expects, you can tweak that number.
Oliver2018 wrote:
Wed Feb 06, 2019 1:28 am
I understood that it is not possible to write the modified 1474560 sector image back to the HD floppy disk because dtc.exe does not provide the Image type (-i4) in write mode.

Is this correct?
Correct.

The kryoflux can only write flux stream .raw, Amiga .adf, .g64, and and Kryoflux IPF images.

They will probably slap me for telling you how to do it, but go to: https://hxc2001.com/download/floppy_dri ... index.html and download the HxC Software tool (you don't need their hardware to run it), feed any 1.44MB IMA, IMG, ImageDisk or Teledisk file to the software and then export as a Kryoflux Stream (don't forget to put the stream file in a folder.). You should then be able to use the Kryoflux DTC to write the resulting stream image.
Note that this is a third party tool and the Kryoflux folks neither endorse nor support that tool. Also, there may be other tools that can do this.

Oliver2018
Posts: 6
Joined: Fri Jan 25, 2019 10:38 pm

Re: Workflow to modify a standard floppy

Post by Oliver2018 » Wed Feb 06, 2019 11:35 pm

Thanks for the tip. I will try to convert a sector image into a stream file with the emulator.

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