Nibtools, ZF and Copy Protection
Joe May
This is SO much nicer than going through a parallel port!
I noticed something interesting and wanted to run it by everyone.
I grabbed one of my originals at random not to heavily copy protected
(Bards Tale II).
Now in the past, I have made a G64 of this and it loaded fine in
Vice.
(Using a different version of Nib-tools which I cant recall and the
XAP1541 parallel cable).
When I tried to create a G64 with ZF, it made it fine and almost
loaded in Vice but hangs.
So I tried it a total of 4 times. (Sometimes it can be a bad read) on
two different drives with the same results.
So I tried doing a straight copy with Burst Nibbler 1.9 on an actual
C64 and the backup loaded fine.
The next thing I will try is to make a .g64 with the ol' XAP1541 again
and see if that still works.
I guess my point is, has anyone tested the ZF with copy protected back-
ups?
Thanks,
Joe
Nate Lawson
> First and foremost, awesome job, thank you!
>
> This is SO much nicer than going through a parallel port!
Thanks.
> I noticed something interesting and wanted to run it by everyone.
>
> I grabbed one of my originals at random not to heavily copy protected
> (Bards Tale II).
>
> Now in the past, I have made a G64 of this and it loaded fine in
> Vice.
> (Using a different version of Nib-tools which I cant recall and the
> XAP1541 parallel cable).
You got lucky.
> When I tried to create a G64 with ZF, it made it fine and almost
> loaded in Vice but hangs.
> So I tried it a total of 4 times. (Sometimes it can be a bad read) on
> two different drives with the same results.
>
> So I tried doing a straight copy with Burst Nibbler 1.9 on an actual
> C64 and the backup loaded fine.
> The next thing I will try is to make a .g64 with the ol' XAP1541 again
> and see if that still works.
Bard's Tale 2 is pirateslayer v2. It has a particular bad GCR pattern on
track 2, usually. This pattern needs to be properly byte-aligned since
VICE interprets G64 as as stream of bytes, not bits as on a real floppy.
To re-frame this pattern in the .nib, you can use the nibshift tool but
Pete doesn't package that with nibtools any more. You can also just
repeat reading it several times and hope to get lucky again.
If you write the .nib back to a blank floppy with nibwrite, it should
work fine.
Burst Nibbler is likely doing some fixups or you just got lucky there.
> I guess my point is, has anyone tested the ZF with copy protected back-
> ups?
Only hundreds of disks over the past few years. :)
--
Nate
Nate Lawson
> On 3/28/2011 2:13 PM, Joe May wrote:
>> So I tried doing a straight copy with Burst Nibbler 1.9 on an actual
>> C64 and the backup loaded fine.
>> The next thing I will try is to make a .g64 with the ol' XAP1541 again
>> and see if that still works.
>
Sorry, read that as "mnib". Burst Nibbler is on a real floppy so it will
copy the pattern as a stream of bits. Same thing should work if you
nibwrite out the G64.
The problem is VICE and its G64 emulation, but you can coerce the data
into a format it likes.
--
Nate
Joe May
I actually never thought about it that way, I will try writing the
data back to floppies and testing them on a real 64 setup.
(For preservation of my original floppy's I don't really care if Vice
can run them or not, as long as I can write them back to a new 5 1/4)
Is there a FAQ somewhere about what protections/g64's Vice can emulate
faithfully? - It would be a nice wiki
I think I may have touched on this with you or Pete I can't remember,
but I also have an original Disk Maker Toolkit from Basix which is
extremely rare!
It can be backed up with Disk Maker's parameters but I don't think
anyone has analyzed its protection.
I will read it with mnib and write it back to see if it works.
Thanks!
Joe
Nate Lawson
> Very Cool!
>
> I actually never thought about it that way, I will try writing the
> data back to floppies and testing them on a real 64 setup.
> (For preservation of my original floppy's I don't really care if Vice
> can run them or not, as long as I can write them back to a new 5 1/4)
Yes, there are various patches that can be made to .nib files (or .g64,
pretty much same thing) that change as little as possible of the
original protection but make it something emulators can handle or can be
written back reliably. Parameters, basically.
> Is there a FAQ somewhere about what protections/g64's Vice can emulate
> faithfully? - It would be a nice wiki
See c64preservation.com for a discussion of the protection schemes, but
unfortunately not much about VICE there.
> I think I may have touched on this with you or Pete I can't remember,
> but I also have an original Disk Maker Toolkit from Basix which is
> extremely rare!
> It can be backed up with Disk Maker's parameters but I don't think
> anyone has analyzed its protection.
> I will read it with mnib and write it back to see if it works.
Sounds interesting. It likely cannot just be written back with nibwrite;
may require some patching. I seem to recall that was one of the tougher
disks.
--
Nate
Pete Rittwage
Yes, the PirateSlayer protection is sync-less, which means the bytes we get back from the drive are 'unframed' or on a random byte-boundary. For this reason, every time you read the track, you have a 1 in 8 shot of getting something VICE will accept. You can make many passes and try it, or you can shift track 2 and try out the 8 different files. I have an older crude program that does this that didn't make it over from the switch to nibtools from mnib. I'll dig it up if you want to play with it.
There is a "protection handler" for it also, but I'll need to check my sources to see if it does the shift for you to align to the correct byte pattern- I don't recall.
I do have at least one set of DiskMaker disks and I believe it was a skew-based protection, meaning the tracks had to be skewed from each other a certain amount- you can check the database on my site.
-
Pete Rittwage
C64 Preservation Project
http://c64preservation.com