24 Oct
2015
24 Oct
'15
7:14 p.m.
On Sat, 24 Oct 2015, Eric Christopherson wrote:
I know Chuck Guzis has written about this, but I
don't see that he's done
so publicly in the last few years, so I thought I'd ask here about his and
others' views on the perennial question of whether (some) 3.5" DSHD disks
can be reliably used in DSDD-only drives. The oft-repeated claim is that
writing can appear to work just fine, but that even a few months later read
errors will occur.
That was certainly the case with 5.25", but THAT was a difference between
300 Oersted and 600 Oersted. WAY OFF.
But, with 3.5" disks, the difference is between 600 Oersted and 720?
Oersted. THAT is close enough.
For BEST results, I think that it would be better to use the right ones,
but unlike 5.25" disks, with 3.5", you can get away with it.
Elsewhere on the page (I don't recall now if it
was Herb or Chuck that said
it) it was conjectured that HD disks that have never been formatted as HD,
-OR- disks that have gone through a good degaussing, will have better luck
retaining data. What does everyone think about this? And would an
electromagnetic library security system (the kind that's like a tube
through which checked-out materials are put; often with a caution not to
put tapes or floppies through it) be a suitable degausser?
Probably a very good idea.
Some Windoze machines will check for existing format before formatting,
and be somewhat uncooperative about reformatting as a different density.
The one time that it is critically important to bulk-erase or use virgin
disks is when writing 48tpi disks in a 96tpi drive. When a 96tpi drive
RE-writes a 48tpi disk, as 48tpi, it can not clear the edges of the track
completely.
Are we really running short of "720K" floppies?
I thought that AOHell had sent out enough snail spam with disks to supply
us forever!