[Coco] 720k 3.5" floppies

Alex Evans alxevans at concentric.net
Tue Nov 6 21:40:29 EST 2007

On  5  Nov 2007, at 7:00 AM, Phill Harvey-Smith wrote:

> Joel Ewy wrote:
>> Maybe I need to dig into my floppy drive stash and do some  
>> testing.  I
>> don't have many real 720K drives (1.44M drives work fine in their  
>> place
>> if you use 720K media -- which is also getting hard to find) but I  
>> have
>> quite a few 360K and 1.2M 5.25" drives, most of which should still  
>> be in
>> good working order.
>> Could one use a 1.2M drive (with HD media) as a 720K drive on a CoCo?
> Nope you'd want to use standard DD media, the difference between a  
> 5.25" 360K disk and a 5.25" 720K disk, is normally that the 360K is  
> 40 tracks double sided, and the 720K is 80 track double sided, but  
> both are double density and not high density. I would imagine using  
> HD media would cause the same problems as for 3.5" drives.

For 5.25" drives the problem is much worse.  An HD 5.25" floppy can  
only rarely be successfully formatted in a DD drive and when it does  
succeed it only works for a very short period of time.  In my  
experience, I have had very very few problems from HD disks in DD  
drives.  In fact some discount manufacturers for a time used the  
exact same film and coating on their DD and HD lines for 3.5" floppies.

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