Re: NIB and DSK questions

[Linards Ticmanis <ticmanis@gmx.de>]

On 02/06/2012 06:27 PM, Egan Ford wrote:

> Is it safe to assume that some .nibs floating around out there were
> created just because that is the imaging format they used?

Some yes, but not many. I think I've read somewhere that some very early
emulators (maybe up to 1993 or so?) used only NIB, both internally and
externally, so it is conceivable that some of the oldest disk images
were made in that format simply because it was the only one around at
that time.

After that time, almost all NIB images were made to preserve some (of
the simpler) copy protection schemes. Since NIB uses fixed track lengths
and doesn't distinguish between sync and non-sync bytes, it's very hard
to write back to real disks correctly, essentially requires manual
intervention.

As for volume numbers: DOS disks store them *inside* some block too, so
emulators that use DSK could use that byte to build the block headers
for the emulated drive to read, instead of defaulting to $FE. Doesn't
help with non-DOS disks though (that includes ProDOS disks), if the
volume number is important on those, NIB is the way to go. No idea why
nobody thought of putting in a one-byte volume number at the end of DSK
but since they didn't, things are as they are: DSK can't preserve volume
numbers on non-DOS disks, even when everything else is totally standard.

-- 
Linards Ticmanis