Re: dsk images

[Rubywand <rubywand@swbell.net>]

Charles T. 'Dr. Tom' Turley writes ...
> 
> Here's the method and steps I use with my Mac to get a .dsk image file
> ready to turn into a real disk for use on my IIgs;
> 
> (A) Get the flipper program for the Mac, ....  will save it as a REAL 
> disk image file (.dsk). ....
>
> Simply copy the xxx.img file to an 800k ProDOS disk, take it out of the
> Mac disk drive and shuttle it over to your IIgs disk drive, ....
> 
> Another alternative .... - is
> to get the NinjaForce Apple II program 'Asimov', copy the disk image
> file to your 800K ProDOS disk on the Mac, take that 800k ProDOS disk
> over to your IIgs, run the NinjaForce Apple II program 'Asimov' and it
> should do the same job for you, resulting in a REAL 5.25 disk of the
> program.
> ....
>

     Lots of details ...; thanks! The mention of _"real"_ DSK files could 
save some users considerable bother. (If I'd read something like this last 
night it could have saved me an hour or so.)


     It is easy to forget that files which show up with names like 
"SUPERQST.DSK" on an ftp site are hardly ever in true DSK file form; they 
are _packed_ DSK files.

     Evidently, on the Asimov site, ".DSK" files are in a zip form and 
could just as well be tagged as ".gz" type packed files. (Sometimes, in 
fact, they are.)  These ".DSK" files can be unpacked on PC using WinZip or 
on a Mac using some similar utility.

     It is pretty easy to tell whether a ".DSK" file is unpacked and ready 
for use or still in packed form. A non-packed single 5.25" DSK file will 
have a length of around 143k-144k.

     A packed ".DSK" file can have a length which is much smaller than 
143k (e.g. 49k). Or, a packed ".DSK" file can include several DSK's 
along with TEXT info files and be fairly large in size (e.g. 179k).

Note: When a packed ".DSK" file is un-zipped, you may end up with an 
unpacked file having the same name. That is, SUNDOG2.DSK may un-zip to an 
unpacked DSK file named "SUNDOG2.DSK". (DSK unpacked disk image files 
almost always end in ".DSK", as they should.)

Consequently, a user should always unzip a ".DSK" file to a different 
directory than the directory in which the original, packed file is 
located. Otherwise, WinZip will over-write your original, discover that it 
is corrupted, and exit. You end up with neither the packed nor the 
unpacked .DSK file! 

     If one downloads a ".DSK" file, unpacks it to get one or more DSK's 
and moves the unpacked ".DSK" files to an Apple ][ (e.g. via a ProDOS 
diskette from Mac or via NULL modem from PC), it is easy to convert each 
DSK file to diskette via DSK2FILE or ASIMOV.

     If one forgets to unpack a freshly downloaded ".DSK" file and moves 
it to an Apple ][, it may, still, seem to make it through the 
DSK-to-diskette conversion; _but_ you will end up with a diskette full of 
garbage, like I did. Eventually, you may see the problem; things just go 
much more smoothly when the screw-up is avoided in the first place.      


Rubywand