🚀 go-pugleaf

In article <chris.3717@genly.UUCP>, chris@genly.UUCP (Chris Hind Genly)
writes:
> I'd like some help understanding the various types of floppies.  I have a
> really old machine at home, an 8088, with a 5 1/4 inch floppy drive that
> works with DS DD disks. I'm running PCDOS 2.10.  I tried to format a 5 1/4
> inch DS HD floppy on my machine and I got an error message along the lines of
> 'track 0 unwritable.' The two types of floppies appear identical to the eye. 
> I assumed that I'd be able to format the HD floppy as a DD floppy and just
> waste the bandwidth.  
> 
>     1) Why can't I format a DS HD diskette as a DS DD disk?

Assuming that you do not have a diskette that has a genuinely "bad" spot
on track 0 (referred to below as the first track), the following may be
useful:

I seem to remember (vaguely) that DOS used to be fussy about formatting
already formatted diskettes to a _different_ format than they were
already formatted to.  Eg.  A DS DD formatted to 320K would not be
re-formatted to 360K, but to 320K.

_Most_ (OK, so yours doesn't! _I_ am yet to see one that don't) DD
drives accurately read the first track of both DD and HD disks (you can
usually do a DIR listing of a HD, but trying to TYPE, COPY or execute
the files results in  a "Sector not found" error, or less often, a "Bad
sector" error.

My guess is that the HD diskettes are pre-formatted and the DOS FORMAT
prog is reading the media-descriptor byte from the FAT OK (cause it's on
that first track).  This tells FORMAT the disk format to use, and
something is going wrong from there - the error message may itself be
erroneously identifying the source of error.  (I doubt that DOS 2.10
knew anything about HD 5 1/4's, so may be spitting over the 1.2M media-
descriptor value it gets - it make "err on the side of caution",
suspecting that it is actually a non-DOS disk and the "unwritable"
message would be something of a warning.)

Now, I'm not sure if this "problem" with FORMAT being "bloody minded"
about this sort of thing is in later versions of DOS or not, so trying
on a PC with a more recent DOS may do the trick, or use a third-party
FORMAT routine (eg. the one in PC-Tools formats to what you select,
regardless of what's already there).
     
>     2) Is there a slot or hole somewhere in the floppy jacket that tells
>        the drive what capacity disk is inserted?

Not with 5 1/4's for DOS-like machines (that I've ever seen - to be on the safe
side 8-) ).
     
>     2) What are the various diskette formats available now, and what
>        are thier capacities?

What school did you go to?   1, 2, 2  ??     8-)

But seriously:  I think this has already been answered in another post.

---------------------------------------------------------------------------
 Nick FitzGerald, PC Applications Consultant, CSC, Uni of Canterbury, N.Z. 
 Internet: n.fitzgerald@csc.canterbury.ac.nz        Phone: (64)(3) 642-337