[Coco] Connect CoCo Floppy drive to Windows PC

[Gene Heskett]

On Saturday 17 January 2009, Fedor Steeman wrote:
>Hi Gene,
>
>2009/1/16 Gene Heskett <gene.heskett at verizon.net>
>
>> Be aware that this is a double edged sword Fedor. The heads on that drive
>> are
>> not wide enough to fully erase old info when over-writing in the 40 tpi
>> mode,
>> and generally there is a 100% chance of trashing the disk.
>
>Hmmm.... Are you saying I had better use a 80 track drive? Or just proceed
>with caution? I have plenty of dispensible ol' diskettes to test with...

It is an 80 track drive, but the drivers will if the os9 descriptors are set 
correctly, double step the drive so as to stay in the center of the wider 40 
track drives recorded track.  It is NOT safe to write to a 40 track formatted 
disk with that drive, so the caution is to treat 40 track disks as 
inviolately read only.  They will be trashed by a write in an 80 track drive 
when next they are read in a 40 track drive because the read will get both 
the old and new data.  Very confusing.

Not also that this (48 tpi vs 96 tpi) situation only exists in the 5.25" 
drives, the 3.5" drives are uniformly 135 tracks per inch, and formatting a 
35 or 40 track format just doesn't use all the disk as they can usually reach 
83 to 85 tracks if you want to play with the descriptors in os9.  The coco 
will not know the difference, relying entirely (in os9) on the data in 
Logical Sector Number Zero (LSN0) to ascertain what sort of a disk it has in 
the drive.  Basic of course is pretty much hard coded as issued, and that 
disk format isn't file structure compatible with os9.

That is also 2 different problems.

-- 
Cheers Fedor, Gene
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