Re: Disks for 3.5" drive

[spector@vax2.concordia.ca (Mitchell Spector)]

In article Tom Zuchowski <71214.1670@CompuServe.COM> writes...
>
><<<The 720k disks will work fine once you reformat them in your 
>Apple.  The HD disks will work, but will cause confusion if you 
>ever put the disk in a Mac drive, say, to transfer data.  I have 
>heard from some sources that the media of the HD disks is actually 
>not compatible with the Apple 800k drives, but I can't verify that 
>from my own experience. >>>
> 
>I certainly can.  I have two AMR drives and an AE drive, and none 
>of them are 100% reliable with HD media.  Perhaps true Apple 
>drives are a little more tolerant (I couldn't say) but I would be 
>very leery of thinking that I could share 800K HD disks with any 
>drive but the one they are made on.

	I've never had problems formatting High-Density 3.5 floppies
as 800K disks, they've sucessfully held data intact for a least the
four years I had them sitting around. From what I've heard, DS/DD
(Double-Density) 3.5 diskettes are merely HD disks that failed to
meet certain tolerance tests at the factory. Whether or not there's
truth to this remains to be seen, but it would explain the notch
imprint (not cut through) on many of my old Double-Density disks.

	You should just be sure to cover up the HD-identification
hole so actual High-Density drives don't get confused. These days
I format HD disks as 1.44MB ProDOS (recently acquired a SuperDrive) 
so it's no longer an issue, unless a disk fails to format. In that
situtation covering the notch and formatting as an 800K disk seems
to work; better than throwing it away (GCR must uses different tracks
than MFM in formatting, thus missing the affected damaged area. Either
that or the drive is less sensitive to errors).

>TomZ

Mitchell Spector
spector@vax2.concordia.ca