Re: HD floppies in a DD drive.

[gberigan@cse.unl.edu (Greg Berigan)]

hbcsc419@huey.csun.edu wrote:

>>cassettes).  I know from sad experience that you CAN format and use the
>>1.44MB diskettes in a conventional A2 800K drive (getting 800K capacity,
>>of course!), but then a few weeks later you'll find that you are getting
>>fatal disk errors and will have lost your data.

>I'd have to differ with you on this one. I've been using HD disks in my
>Apple 3.5" 800k drive for 2 years now, and have had no fatal disk errors.

Same here, but for a longer time.  I have had no fatal disk errors that
can be attributed to formatting HD disks to DD size.  Indeed, I get more
errors from real DD disks as they get corruption of -- more often than
not -- block 0002 only (first block of ProDOS directory).  I've since
made sure I never store any actual files in the root directory of a
disk.  I only place directories there so that, if block 0002 is lost,
the subdirectories are still good.  (If there is a way to patch ProDOS
so that it looks at block 0003 as the first block of the root directory
(or any other block), I'd appreciate a copy of that patch.  I know DOS
3.3 could be told to use something other than track $11.  I'll sacrifice
being able to boot such disks if necessary.)

One thing you should do when you format an HD disk as DD is to take one
of those write protect tabs used with 5.25" disks and place it over the
HD hole in the HD disk.  Mac HD drives can read DD disks, but if you try
to put an HD disk formmatted DD in the drive, it isn't smart enough to
realize that the disk was formatted DD and will ask you to format it.
Covering up the HD hole of the disk makes the HD drive recognize it as a
DD disk.

My old high school had this exact same problem when they first started
getting Macs with HD drives.  They had lots of HD disks formatted DD
_on_Macs_ that were showing up as bad on the new computers.

I don't regularly format HD disks as DD disks anymore though ever since
I've moved lots of files from disks to hard drives.  I now have an
overabundance of blank HD and DD disks which I format to their designed
capacities whenever possible.  (I have come across some so badly damaged
that they could only be formatted to 400K.  Damaged disks I use for very
temporary storage like footnetting files between systems or as coasters
and frisbees.)

On the mention of bulk purchases, a friend bought disks from one store
that purchased their disks in bulk.  He had come across some interesting
5.25" "100% certified" disks while they were getting disks from a
particular company.  One disk had no disk inside the jacket.  Another had
_two_ disks in one jacket (and wouldn't turn).

One looked fine, but wouldn't format.  Looking at the disk, he saw that
the formatting started to take off the magnetic surface from the disk.
Touching it showed it would come off at the slightest touch.  He did
this to the whole disk so that all that was left was the transparent
acetate disk the magnetic material was placed on an brought it back to
the store saying, "Now _that_ is what I call a blank disk!"

The store never ordered disks by bulk from that company again.  They
also managed to sell off all their remaining defective disks from that
company to a competitor for them to sell. :-)

-- 
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