Re: .DSK images with 40 tracks?

[pausch@saaf.se (Paul Schlyter)]

In article <20030311210824.19751.00003447@mb-cu.aol.com>,
Michael J. Mahon <mjmahon@aol.com> wrote:
 
> In article <3E6E5E8C.30302@nowhere.net>, Default <noone@nowhere.net> writes:
> 
>> Only the original Disk ][ drives did not support 40 tracks, the 
>> supported a 36th though.  The standard format for the II line of 
>> computers is 35 tracks and that is why the standard is set there.  I 
>> agree that additional track support is easily enough done in the 
>> emulator, but you would need a patched DOS that also supports it with 
>> 5.25" images.
> 
> Unless I'm wrong, DOS and ProDOS are parameterized by values
> in the VTOC/root directory, and do not require any customization
> to use a larger-than-usual disk, only to format one.
 
Quite true.  DOS is only capable of handling disk sizes up to about
400K, but within that size limit, DOS will read the disk size off
the VTOC and adjust itself to it.  The only modifications which may be
needed will be in the RWTS to handle the larger disk at a lower level.
 
Personally I used 640K disks (80-track double sided) for years with
Apple CP/M and Apple DOS.  On Apple DOS I had to split the 640K disk
into two DOS "volumes" -- I distinguished them by adding drives 3 and
4: thus the first disk had drive 1 and 3, and the second disk had
drive 2 and 4, and one "volume" was on one side of the disk.  Anyway,
apart from some modifications to the RWTS and proper formatting of
these disks, no changes whatsoever needed to be done to Apple DOS.
 
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