'Tools to work on g64 et al'
Author:Nate (guest: search)
Date: Tue, Jun 21st, 2011 @ 00:35 ( . )

On 06/20/2011 @ 13:35, hyper active wrote :
Hiya.
: Will your program work on nb2 files?
: Nibread allows you to dump a track or tracks multiple times and read it out in several different densities.
: Thanks.
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I've been busy and haven't finished this tool yet.

Not yet but I'll consider supporting them. You can always work with g64s pieced together from each density track.

BTW, I've always thought nibread should read data at the fastest bitrate and then downsample in nibconv. Is there any problem with this? That way any of the slower bitrate density settings could be recreated in software and tracks wouldn't have to be re-read.


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'Tools to work on g64 et al'
Author:Pete Rittwage (registered user: 558 posts )
Date: Tue, Jun 21st, 2011 @ 09:37 ( . )

I recall trying that at some point, but the problem is that you often lose framing when reading at the wrong bit rate, and it can't be put back together again reliably. Timing isn't perfect on belt driven drives and at unknown rotation speed, and I don't think you can test rotation speed without writing data.

Even worse, some drives (some 1541-II's especially) will return random data that isn't based on the actual flux stream, when out of framing.

I can look at it again if there's something I missed, though.


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'Tools to work on g64 et al'
Author:Nate (guest: search)
Date: Wed, Jun 22nd, 2011 @ 13:14 ( . )

Yeah, I understand that if you have a low density of 1 bits, choosing a bitrate setting that is too high would result in spurious 1's being clocked into the shift register.

Basically, you'd be creating "weak bits" if reading a low bitrate source at a higher rate.


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'Tools to work on g64 et al'
Author:Pete Rittwage (registered user: 558 posts )
Date: Sat, Jul 02nd, 2011 @ 15:02 ( . )

I can try reading all at the lowest density and calculating. Do you have a routine to recalculate at another bit rate that I can experiment with?


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'Tools to work on g64 et al'
Author:Pete Rittwage (registered user: 558 posts )
Date: Sat, Jul 02nd, 2011 @ 15:02 ( . )

Pseudo-code or an explanation would be fine...


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'Tools to work on g64 et al'
Author:Fungus (registered user: 20 posts )
Date: Sun, Jul 03rd, 2011 @ 07:50 ( . )

I don't think 1571's and 1541-II's should be used on some disks to dump with as they don't function exactly the same as an older 1541. Been researching some of the hardware differences, so that vice disk emulation can be re-done lately. I've found that II's and 71's can not read with byte_sync disabled, it simply does not work at all on those drives.

That's the reason some games were released again with changes to the protection so that they would function on those drives. Star Rank Boxing is an excellent example of this, due to the way it checks the syncs and data before and after them.

Lord Crass can explain how these checks work in greater detail than I can at the moment. =]

Reading disks with multiple densities on a track or abnormal densities is just going to be a problem on any drive, the protections which do such stuff need to be analyzed and custom dumping would have to be done for such disks as you know it's a bit hard to auto detect the density reliably.

Also, very much looking forward to the release of G64/NIB editor. I can't wait ;)


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'Tools to work on g64 et al'
Author:hyper active (registered user: 296 posts )
Date: Wed, Jul 13th, 2011 @ 00:46 ( . )

si.
Huri! Huri! Huri!


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