A9M0107 disk compatability

[Sean Downs]

Will these disks work for my 5.25 drive?

http://www.ebay.com/itm/New-SONY-5-25-5-1-4-FLOPPY-DISKETTES-Disks-SSDD-180k-Factory-Sealed-Box-of-10-/221231397978?pt=US_Vintage_Computing_Parts_Accessories&hash=item33826b3c5a

or

http://www.ebay.com/itm/New-SYNCOM-5-25-5-1-4-FLOPPY-DISKETTES-Disks-DSDD-360k-Factory-Sealed-Box-10-/221231400394?pt=US_Vintage_Computing_Parts_Accessories&hash=item33826b45ca

if not (or even if so), what kind of disks can this use. Will the 360k or 800k still work, just not the opposite side?

Please help.

Thanks,
Sean

[David Schmidt]

On 6/18/2013 4:08 AM, Sean Downs wrote:
> Will these disks work for my 5.25 drive?
>
> http://www.ebay.com/itm/New-SONY-5-25-5-1-4-FLOPPY-DISKETTES-Disks-SSDD-180k-Factory-Sealed-Box-of-10-/221231397978?pt=US_Vintage_Computing_Parts_Accessories&hash=item33826b3c5a
>
> or
>
> http://www.ebay.com/itm/New-SYNCOM-5-25-5-1-4-FLOPPY-DISKETTES-Disks-DSDD-360k-Factory-Sealed-Box-10-/221231400394?pt=US_Vintage_Computing_Parts_Accessories&hash=item33826b45ca

Yes. They are double (not high) density.

> if not (or even if so), what kind of disks can this use. Will the 360k or 800k still work, just not the opposite side?

Disks will be labeled DD, or Double Density, 360k up to 500k. (Not
800k... that's a 3.5" designation). Sidedness doesn't really matter.

Single sided meant that only one side was "certified" to work; in
practice, both sides will generally work. It only mattered for disks
manufactured very, very early on. It's not a great practice to flip a
floppy over, though, because the pressure pad on the "other" side of
your drive is wiping the surface instead of a ceramic read head. Not
fatal, but if you can avoid it... why do it?

[Patrick Schaefer]

Am 18.06.2013 13:32 schrieb David Schmidt:

> Single sided meant that only one side was "certified" to work; in
> practice, both sides will generally work.

The biggest issue with single-sided disks is that the never mention
which side has been tested. Some single-sided drives have the RW head on
the bottom, some on the top.

> It's not a great practice to flip a
> floppy over, though, because the pressure pad on the "other" side of
> your drive is wiping the surface instead of a ceramic read head. Not
> fatal, but if you can avoid it... why do it?

A double-sided drive has the heads shifted by 1/2 track. So that the
field that penetrated from one side to the other goes between two
tracks. If you flip the disk, the tracks on both sides are directly
opposite to each other.


Patrick

[Michael Black]

On Tue, 18 Jun 2013, Patrick Schaefer wrote:

> Am 18.06.2013 13:32 schrieb David Schmidt:
>
>> Single sided meant that only one side was "certified" to work; in
>> practice, both sides will generally work.
>
> The biggest issue with single-sided disks is that the never mention which
> side has been tested. Some single-sided drives have the RW head on the
> bottom, some on the top.
>

Is that true? I never had a single sided drive (my first drive was double
sided, for the Radio Shack COlor COmpuer). I remember when I first
brought that first drive home, I wondered which way to put the disc in (it
wnas't obvious. When I got a second drive, I'm not so sure I mounted it
"right side up", just that I mounted it so the floppy went in the same way
as on the first drive.

If single sided drives were variable about which side the head was on,
then both sides of the floppy would have had to be certified. Yet from the
moment people started using single sided floppies on both sides, the issue
of "not being certified" was always mentioned.

Michael

[Sean Downs]

Thanks for that. the manual says 140k, some sites say other things. Being able to ask here is pretty, so thanks again.
Sean

[David Schmidt]

On 6/18/2013 8:27 PM, Sean Downs wrote:
> Thanks for that. the manual says 140k, some sites say other things.

Yeah, the Apple II only makes use of 140k of a disk. But of course
that's only using one side of the disk, and it's not as efficient as it
could be, only using 35 out of a possible 40-ish tracks. And then
there's GCR vs. MFM... anyway, there's lots and lots of reasons why the
numbers never quite match up. Somewhere south of a megabyte is what you
can theoretically and practically stuff onto a DD disk, given the right
hardware and software (which the stock Apple II disk controller does not
possess).