Re: How to make .nib disk images?

[pausch@saaf.se (Paul Schlyter)]

In article <3D6270E9.4963218B@hotmail.com>,
Ron Kneusel  <oneelkruns@hotmail.com> wrote:
 
>Rubywand wrote:
>>      Seems like I read somewhere that the old time .nib maker program (SST)
>> uses bit copy routines from Essential Data Duplicator (EDD). Instead of
>> writing the copy to another disk, SST writes the stuff as data to a couple
>> of disks. I think the data probably looks like what you get when you do
>> a 'raw track' display under most bit copiers.
>
>This is a little closer to what I want.
>
>Basically, I want to add .nib format creation to DSK2FILE.  I can read
>the raw track data easily enough but what I lack is information on how
>to package that data into a .nib format disk image.  For example:
>
>-- How many self-sync bytes to include between tracks, address fields,
>data fields?
 
Perhaps half-a-dozen between address and data fields, and perhaps
two dozen between sectors.
 
Tracks are distinguished by fixed locations in the .nib files: all
tracks on a real floppy don't have exactly the same number of bytes,
but on a .nib image they should have: fill out with FF's, or
truncate, as needed.
 
And on a .nib image there are no self-sync bytes really (since a
self-sync byte on a floppy is 10 times: eight '1' bits followed by
two '0' bits).  Self-sync isn't needed in a .nib image, since you're
able to determine when a byte starts on any disk file, including .nib
image files.
 
>-- Is there an expectation that the .nib image start with the address
>field header
>   for track 0 sector 0?  This part of every bootable disk is "normal"
>(for the most
>   part) otherwise the disk controller couldn't read the disk.
 
Probably.  Examine some actual .nib images and find out!
 
>-- Must each track be a set number of bytes long?
 
Yes:  find a .nib disk image file, divide its size with 35 and you'll
get the number of bytes each track is supposed to have.
 
>These are the sorts of questions I'm looking to answer.  Perhaps I am
>making the problem more difficult than is necessary.  The disks I want
>to make images of are not particularly well protected, for the most part
>they only permute the address and data field header bytes.  No sync'ed
>tracks or half-tracks.
>
>>      There may be a few cases where the closer (slower) drive emulation
>> option available in Apple Oasis makes a difference in using a .nib
>> image of protected software. In most cases, speed doesn't seem to matter
>> and AppleWin works fine.
>
>I've seen some, possibly old, source code for AppleWin and for .nib
>images it is looking specifically for the proper DOS/ProDOS header bytes
>and so would fail on the 
>disks I'm looking to make images of.
>
>Ron
-- 
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