'Tools to work on g64 et al'
Author:Nate (guest: search)
Date: Sun, Apr 10th, 2011 @ 13:34 ( . )

Made some more progress on this and now have some questions. The code currently lets you do the following by editing the text dump of an image:

* Read/write .nib or .g64
* Insert, change, delete GCR bytes
* Change SYNC length, delete SYNCs, add them, etc.
* Format is 5:4 bytes (GCR to decoded), two sets of these per line (10 bytes GCR)

There are also commands to do the following:

* Shift track: output 7 .nib or .g64 files with rotates of 1 to 7 bits for a given track #

I'm looking at adding support for these features but uncertain which ones are most useful:

* Align a given track (rotate in image), based on the following:

- First sync found (10 bits of 1)
- Sector number (does some decoding)
- GCR pattern

Are there any others that would be useful? Start track at longest sync?

Of course, you can implement arbitrary track-to-track alignments with this by rotating track 1 to start at sector 0, track 2 to sector 15, or whatever.

* Density conversion -- How should this be done? I understand that if you want to convert a range of data from higer density to lower, you just discard bits. But I think there's no way to go from lower to higher.

For density, I support the g64 per-byte extended map so you can set arbitrary density for byte ranges within each track. Of course, you lose that info if you write out a .nib.

Comments welcome.


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Replies:
--* Tools to work on g64 et al
4/10/2011 @ 21:00--Pete Rittwage
4/12/2011 @ 22:11----Nate
4/12/2011 @ 22:58------Pete Rittwage
4/13/2011 @ 11:00--Lord Crass
4/14/2011 @ 17:29----Nate
4/14/2011 @ 19:56------Lord Crass
4/14/2011 @ 20:25--------Pete Rittwage
4/15/2011 @ 23:10------J Achernar

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