Re: DSDD vs DSHD disks

[grent@comcast.net (Geo3)]

"Joel" <joelbuckley54.nospam.@hotmail.com> wrote in message news:<IG-dnc1r2vLTwSCgXTWcqg@comcast.com>...
> "Quadrajet1" <quadrajet1@aol.com> wrote in message
> 20021028070606.24168.00001132@mb-md.aol.com">news:20021028070606.24168.00001132@mb-md.aol.com...
> > << "Adam Barr" <omashiroi@yahoo.com> wrote in message
> > 4b54956e.0210272035.1d0531e2@posting.google.com">news:4b54956e.0210272035.1d0531e2@posting.google.com...
> > > Does any one know a place that still sells new 5.25" disks? Thanks!
> > > -Adam
> >
> >    I have a bunch of blank 5.25 disks without jackets. They are white in
>  color
> > too. Problem is, how do I tell the difference between DS/DD and DS/HD?
>  There
> > are no extra notches or markings that I am aware of, like in 3.5 disks.
> >
> >   I do run across 5.25 DS/DD disks all the time brand new in the thrift
>  stores,
> > etc all the time however.
> >
> > Raymond
> 
> I don't believe there are obvious ways to tell 360 vs 1.2M 5.25 disks.
> I don't know if this is standard or coincidence, but in looking at some of
> mine,
> the HD disk recording surface is much darker in color, blackish gray, shiny,
> while the DD is lighter, sort of brownish gray and flatter, not so shiny.
> This seems to hold up with several different brands.
> By memory, a DD disk will seldom format at HD.
> And while a HD disk will format at DD in an IBM computer, these disks can't
> be reliably read on a DD drive.
> It's not just a function of the head size and track width being smaller.
> The magnetic characteristics of the media are different.
> My memory is that HD disks did not work reliably in an Apple II.
> 
> Of course, the real spec for an Apple II disk is SSSD.
> How do you tell them apart from DSDD?
> And it was common practice to flip the disks over and use both sides even
> though DS spec doesn't really call for the disks to be rotating the opposite
> direction.

Hi,
 The easiest way to low from High is that the HD I have run across
have all have no center hub. No metal ring. Apple Disk Drive II can
not clamp on these very well. They also tend to damage the center if
there is no hub. Sometimes the hub has fallen off due to age, this
rare but does happen. Newer stlye apple drives clamp a little better
on these. But I would transfer anything off these befor you would have
problems.
  Take Care,
        George