Mastering C64 Disks: How-To?

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8bit-Dude
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Joined: Sat Apr 10, 2021 12:09 pm

Mastering C64 Disks: How-To?

Post by 8bit-Dude »

Hey Guyz,

I am new here, and hoping to get some help. ;)

I bought the KryoFlux and a TEAC FD-55GFR, in the hope of mass-writing floppies for a C64 game I plan to sell (copying on my 1571 is just too slow for practical purpose, and I don't want to knacker my drive anyway).

So first of all, I tried to write the Defender of the Crown G64 example (using -dd1). That worked fine for side 0 (I could not figure out how to write side 1, a hardware mod on the drive is perhaps required?). Anyway, side 0 read perfectly on 1571 drive.

Next, I tried to directly convert my D64 file (produced with 1541.exe) to a KryoFlux stream with HxC. The stream files were exported correctly, but I could not get DTC to write a disk from them (it complained about not knowing what the files are, or something like that).

Not giving up yet, I transferred my D64 to floppy directly on the C64 using a SD card reader, 1571 and DraCopy. That took a while, after which I confirmed that the disk could load properly from the 1571.

Last step, I tried to duplicate the C64 made disk using (I tried both with/without -dd1):

dtc -p -b-8 -fstream/dump -i0 -g0 -i6 -dd1
dtc -fstream/dump -w -dd1

The disk was recognized by the 1571 and showed the correct directory listing. But I cannot load the files properly, I get read errors everytime (I tried with 3 disks, each time starting from a virgin, good quality, mid-2000s era floppies).

So here are my questions:

(1) I know that the floppies and disk must be good, since I was able to write and load DOC correctly. Is there something I should do with the commands above that will improve my chance of duplicating the disk correctly?

(2) Is there a trick with HxC to export the D64 as a stream that DTC will accept as input? It would be very convenient to be able to export directly from my laptop, without going through the C64 first (it is THAT slow!)

Thanks in advance!
Tony
brightcaster
Posts: 405
Joined: Fri Nov 08, 2013 10:48 pm

Re: Mastering C64 Disks: How-To?

Post by brightcaster »

The Teac FD-55GFR is a 80 track drive with 96tpi. The commodore drives have 40 tracks with 48tpi. That doesn't fit well...

Details are described in this thread:

viewtopic.php?f=10&t=1653&p=14810&hilit ... ive#p14810

David
8bit-Dude
Posts: 2
Joined: Sat Apr 10, 2021 12:09 pm

Re: Mastering C64 Disks: How-To?

Post by 8bit-Dude »

Hmmm, so basically I should try with a 360KB drive for better results?
SomeGuy
Posts: 319
Joined: Wed Feb 18, 2015 8:18 pm

Re: Mastering C64 Disks: How-To?

Post by SomeGuy »

There are a couple of problems here:

First, PC 360k drives usually can't handle GCR.

Second, the Kryoflux can not write disk images that are not index aligned. (Anything written natively by a C64 will not be index aligned)

Third, I believe that the Kryoflux will force double stepping, and therefore the use of a 1.2mb drive when writing "D64" files.

Fourth, if the source image file contains both sides of a "flippy" disk, then you will need a flippy modded drive.

Your best bet to get this working is to thoroughly degauss the destination disk before writing it with the Kryoflux in your 1.2mb drive. I believe that is the official way the Kryoflux designers want. Without a flippy modded drive, you will be able to write only the first side. If the kryoflux does not clobber the second side, you may be able to flip the disk over in the 1.2mb drive to write a second side, but that requires a second index hole opening in the floppy disk jacket.
brightcaster
Posts: 405
Joined: Fri Nov 08, 2013 10:48 pm

Re: Mastering C64 Disks: How-To?

Post by brightcaster »

Yes, writing of G64 images forces double stepping. But raw dumps could be written with single stepping on 360k drives! I guess it's the reading only where 360k drives have problems with GCR (due to AGC filtering etc.).

David
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IFW
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Re: Mastering C64 Disks: How-To?

Post by IFW »

Yes, AGC very much depends on the drive used, if you have problems with that - or better, even if you don't - set the -dd parameter for reading, usually (but not necessarily) -dd1.
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IFW
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Re: Mastering C64 Disks: How-To?

Post by IFW »

Also quite some C64 disks cannot be written back to a real disk without a 80 track drive, e.g. tons of disks with XEMAG protection aka "fat tracks".
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IFW
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Re: Mastering C64 Disks: How-To?

Post by IFW »

As for index synced writing, the current DTC version cannot "blindly" copy a disk that is not index synced.
It can replicate a non-index synced disk perfectly fine from either a g64 with mastering data (generated by DTC as -i22a) or IPF file - there are quite a lot of both types that are not index synced.
When such data is available in the disk format, DTC times writing of the start of the track according to the timings recorded in the file.

My recommendation would be for your C64 disk to be duplicated is to create a -i22a format disk of it, and it will be written (and verified!) properly even if the tracks are not index aligned.
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